[singular][issue #2221] the plural builder method now nullchecks its argument with configurable results.

79 files changed, 835 insertions, 108 deletions

diff --git a/src/core/lombok/ConfigurationKeys.java b/src/core/lombok/ConfigurationKeys.java
index ef433d8d..691346cd 100644
--- a/src/core/lombok/ConfigurationKeys.java
+++ b/src/core/lombok/ConfigurationKeys.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2013-2019 The Project Lombok Authors.
+ * Copyright (C) 2013-2020 The Project Lombok Authors.
  * 
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -23,12 +23,13 @@ package lombok;
 
 import java.util.List;
 
+import lombok.Singular.NullCollectionBehavior;
 import lombok.core.configuration.CallSuperType;
 import lombok.core.configuration.CheckerFrameworkVersion;
 import lombok.core.configuration.ConfigurationKey;
-import lombok.core.configuration.LogDeclaration;
 import lombok.core.configuration.FlagUsageType;
 import lombok.core.configuration.IdentifierName;
+import lombok.core.configuration.LogDeclaration;
 import lombok.core.configuration.NullCheckExceptionType;
 import lombok.core.configuration.TypeName;
 
@@ -287,7 +288,19 @@ public class ConfigurationKeys {
 	 * 
 	 * By default or if explicitly set to {@code true}, lombok will attempt to automatically singularize the name of your variable/parameter when using {@code @Singular}; the name is assumed to be written in english, and a plural. If explicitly to {@code false}, you must always specify the singular form; this is especially useful if your identifiers are in a foreign language.
 	 */
-	public static final ConfigurationKey<Boolean> SINGULAR_AUTO = new ConfigurationKey<Boolean>("lombok.singular.auto", "If true (default): Automatically singularize the assumed-to-be-plural name of your variable/parameter when using {@code @Singular}.") {}; 
+	public static final ConfigurationKey<Boolean> SINGULAR_AUTO = new ConfigurationKey<Boolean>("lombok.singular.auto", "If true (default): Automatically singularize the assumed-to-be-plural name of your variable/parameter when using @Singular.") {}; 
+	
+	/**
+	 * lombok configuration: {@code lombok.singular.nullCollections} = one of: [{@code NullPointerException}, {@code IllegalArgumentException}, {@code JDK}, {@code Guava}, or {@code ignore}].
+	 * 
+	 * Lombok generates a 'plural form' method, which takes in a collection and will <em>add</em> each element in it to the {@code @Singular} marked target. What should happen if {@code null} is passed instead of a collection instance?<ul>
+	 * <li>If the chosen configuration is {@code NullPointerException} (the default), or {@code IllegalArgumentException}, that exception type is a thrown, with as message <code><em>field-name</em> must not be null</code>.</li>
+	 * <li>If the chosen configuration is {@code JDK}, a call to {@code java.util.Objects.requireNonNull} is generated with the fieldname passed along (which throws {@code NullPointerException}).</li>
+	 * <li>If the chosen configuration is {@code Guava}, a call to {@code com.google.common.base.Preconditions.checkNotNull} is generated with the fieldname passed along (which throws {@code NullPointerException}).</li>
+	 * <li>If the chosen configuration is {@code Ignore}, then no exception occurs, and the call does nothing; it acts as if an empty collection was passed.</li>
+	 * </ul>
+	 */
+	public static final ConfigurationKey<NullCollectionBehavior> SINGULAR_NULL_COLLECTIONS = new ConfigurationKey<NullCollectionBehavior>("lombok.singular.nullCollections", "Lombok generates a method to add all elements in a collection when using @Singular. What should happen if a null ref is passed? default: throw NullPointerException.") {};
 	
 	// ##### Standalones #####
 	
@@ -312,10 +325,14 @@ public class ConfigurationKeys {
 	// ----- NonNull -----
 	
 	/**
-	 * lombok configuration: {@code lombok.nonNull.exceptionType} = one of: [{@code IllegalArgumentException}, {@code NullPointerException}, or {@code Assertion}].
+	 * lombok configuration: {@code lombok.nonNull.exceptionType} = one of: [{@code IllegalArgumentException}, {@code NullPointerException}, {@code JDK}, {@code Guava}, or {@code Assertion}].
 	 * 
-	 * Sets the exception to throw if {@code @NonNull} is applied to a method parameter, and a caller passes in {@code null}. If the chosen configuration is {@code Assertion}, an assertion is generated instead,
-	 * which would mean your code throws an {@code AssertionError} if assertions are enabled, and does nothing if assertions are not enabled.
+	 * Sets the behavior of the generated nullcheck if {@code @NonNull} is applied to a method parameter, and a caller passes in {@code null}.<ul>
+	 * <li>If the chosen configuration is {@code NullPointerException} (the default), or {@code IllegalArgumentException}, that exception type is a thrown, with as message <code><em>field-name</em> is marked non-null but is null</code>.</li>
+	 * <li>If the chosen configuration is {@code Assert}, then an {@code assert} statement is generated. This means an {@code AssertionError} will be thrown if assertions are on (VM started with {@code -ea} parameter), and nothing happens if not.</li>
+	 * <li>If the chosen configuration is {@code JDK}, a call to {@code java.util.Objects.requireNonNull} is generated with the fieldname passed along (which throws {@code NullPointerException}).</li>
+	 * <li>If the chosen configuration is {@code Guava}, a call to {@code com.google.common.base.Preconditions.checkNotNull} is generated with the fieldname passed along (which throws {@code NullPointerException}).</li>
+	 * </ul>
 	 */
 	public static final ConfigurationKey<NullCheckExceptionType> NON_NULL_EXCEPTION_TYPE = new ConfigurationKey<NullCheckExceptionType>("lombok.nonNull.exceptionType", "The type of the exception to throw if a passed-in argument is null (Default: NullPointerException).") {};
 	
diff --git a/src/core/lombok/Singular.java b/src/core/lombok/Singular.java
index 67edab96..f8cf6853 100644
--- a/src/core/lombok/Singular.java
+++ b/src/core/lombok/Singular.java
@@ -27,6 +27,10 @@ import static java.lang.annotation.RetentionPolicy.*;
 import java.lang.annotation.Retention;
 import java.lang.annotation.Target;
 
+import lombok.core.LombokImmutableList;
+import lombok.core.configuration.ExampleValueString;
+import lombok.core.configuration.NullCheckExceptionType;
+
 /**
  * The singular annotation is used together with {@code @Builder} to create single element 'add' methods in the builder for collections.
  */
@@ -35,4 +39,64 @@ import java.lang.annotation.Target;
 public @interface Singular {
 	/** @return The singular name of this field. If it's a normal english plural, lombok will figure it out automatically. Otherwise, this parameter is mandatory. */
 	String value() default "";
+	
+	NullCollectionBehavior nullBehavior() default NullCollectionBehavior.NULL_POINTER_EXCEPTION;
+	
+	@ExampleValueString("[NullPointerException | IllegalArgumentException | JDK | Guava | Ignore]")
+	public enum NullCollectionBehavior {
+		ILLEGAL_ARGUMENT_EXCEPTION {
+			@Override public String getExceptionType() {
+				return NullCheckExceptionType.ILLEGAL_ARGUMENT_EXCEPTION.getExceptionType();
+			}
+			
+			@Override public LombokImmutableList<String> getMethod() {
+				return NullCheckExceptionType.ILLEGAL_ARGUMENT_EXCEPTION.getMethod();
+			}
+		},
+		NULL_POINTER_EXCEPTION {
+			@Override public String getExceptionType() {
+				return NullCheckExceptionType.NULL_POINTER_EXCEPTION.getExceptionType();
+			}
+			
+			@Override public LombokImmutableList<String> getMethod() {
+				return NullCheckExceptionType.NULL_POINTER_EXCEPTION.getMethod();
+			}
+		},
+		JDK {
+			@Override public String getExceptionType() {
+				return NullCheckExceptionType.JDK.getExceptionType();
+			}
+			
+			@Override public LombokImmutableList<String> getMethod() {
+				return NullCheckExceptionType.JDK.getMethod();
+			}
+		},
+		GUAVA {
+			@Override public String getExceptionType() {
+				return NullCheckExceptionType.GUAVA.getExceptionType();
+			}
+			
+			@Override public LombokImmutableList<String> getMethod() {
+				return NullCheckExceptionType.GUAVA.getMethod();
+			}
+		},
+		IGNORE {
+			@Override public String getExceptionType() {
+				return null;
+			}
+			
+			@Override public LombokImmutableList<String> getMethod() {
+				return null;
+			}
+		};
+		
+		
+		public String toExceptionMessage(String fieldName) {
+			return fieldName + " cannot be null";
+		}
+		
+		public abstract String getExceptionType();
+		
+		public abstract LombokImmutableList<String> getMethod();
+	}
 }
diff --git a/src/core/lombok/core/configuration/NullCheckExceptionType.java b/src/core/lombok/core/configuration/NullCheckExceptionType.java
index 3c9e325d..4632916c 100644
--- a/src/core/lombok/core/configuration/NullCheckExceptionType.java
+++ b/src/core/lombok/core/configuration/NullCheckExceptionType.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014-2019 The Project Lombok Authors.
+ * Copyright (C) 2014-2020 The Project Lombok Authors.
  * 
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -23,7 +23,7 @@ package lombok.core.configuration;
 
 import lombok.core.LombokImmutableList;
 
-@ExampleValueString("[NullPointerException | IllegalArgumentException | Assertion | JDK | GUAVA]")
+@ExampleValueString("[NullPointerException | IllegalArgumentException | Assertion | JDK | Guava]")
 public enum NullCheckExceptionType {
 	ILLEGAL_ARGUMENT_EXCEPTION {
 		@Override public String getExceptionType() {
diff --git a/src/core/lombok/core/handlers/HandlerUtil.java b/src/core/lombok/core/handlers/HandlerUtil.java
index 38aada23..883b1a29 100644
--- a/src/core/lombok/core/handlers/HandlerUtil.java
+++ b/src/core/lombok/core/handlers/HandlerUtil.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2013-2018 The Project Lombok Authors.
+ * Copyright (C) 2013-2020 The Project Lombok Authors.
  * 
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -451,11 +451,6 @@ public class HandlerUtil {
 		return null;
 	}
 	
-	/* NB: 'notnull' is not part of the pattern because there are lots of @NotNull annotations out there that are crappily named and actually mean
-	        something else, such as 'this field must not be null _when saved to the db_ but its perfectly okay to start out as such, and a no-args
-	        constructor and the implied starts-out-as-null state that goes with it is in fact mandatory' which happens with javax.validation.constraints.NotNull.
-	        Various problems with spring have also been reported. See issue #287, issue #271, and issue #43. */
-	
 	public static final String DEFAULT_EXCEPTION_FOR_NON_NULL = "java.lang.NullPointerException";
 	
 	/**
diff --git a/src/core/lombok/eclipse/handlers/EclipseSingularsRecipes.java b/src/core/lombok/eclipse/handlers/EclipseSingularsRecipes.java
index 9d79d75c..5fe4b958 100755
--- a/src/core/lombok/eclipse/handlers/EclipseSingularsRecipes.java
+++ b/src/core/lombok/eclipse/handlers/EclipseSingularsRecipes.java
@@ -33,25 +33,31 @@ import java.util.Map;
 
 import org.eclipse.jdt.internal.compiler.ast.ASTNode;
 import org.eclipse.jdt.internal.compiler.ast.AbstractMethodDeclaration;
+import org.eclipse.jdt.internal.compiler.ast.AllocationExpression;
 import org.eclipse.jdt.internal.compiler.ast.Annotation;
+import org.eclipse.jdt.internal.compiler.ast.Block;
 import org.eclipse.jdt.internal.compiler.ast.ConditionalExpression;
 import org.eclipse.jdt.internal.compiler.ast.EqualExpression;
 import org.eclipse.jdt.internal.compiler.ast.Expression;
 import org.eclipse.jdt.internal.compiler.ast.FieldDeclaration;
 import org.eclipse.jdt.internal.compiler.ast.FieldReference;
+import org.eclipse.jdt.internal.compiler.ast.IfStatement;
 import org.eclipse.jdt.internal.compiler.ast.IntLiteral;
 import org.eclipse.jdt.internal.compiler.ast.MessageSend;
 import org.eclipse.jdt.internal.compiler.ast.NullLiteral;
 import org.eclipse.jdt.internal.compiler.ast.OperatorIds;
 import org.eclipse.jdt.internal.compiler.ast.ParameterizedQualifiedTypeReference;
 import org.eclipse.jdt.internal.compiler.ast.ParameterizedSingleTypeReference;
+import org.eclipse.jdt.internal.compiler.ast.QualifiedNameReference;
 import org.eclipse.jdt.internal.compiler.ast.QualifiedTypeReference;
 import org.eclipse.jdt.internal.compiler.ast.Reference;
 import org.eclipse.jdt.internal.compiler.ast.ReturnStatement;
 import org.eclipse.jdt.internal.compiler.ast.SingleNameReference;
 import org.eclipse.jdt.internal.compiler.ast.SingleTypeReference;
 import org.eclipse.jdt.internal.compiler.ast.Statement;
+import org.eclipse.jdt.internal.compiler.ast.StringLiteral;
 import org.eclipse.jdt.internal.compiler.ast.ThisReference;
+import org.eclipse.jdt.internal.compiler.ast.ThrowStatement;
 import org.eclipse.jdt.internal.compiler.ast.TypeReference;
 import org.eclipse.jdt.internal.compiler.ast.Wildcard;
 import org.eclipse.jdt.internal.compiler.lookup.ClassScope;
@@ -60,10 +66,12 @@ import org.eclipse.jdt.internal.compiler.lookup.TypeConstants;
 import org.eclipse.jdt.internal.compiler.lookup.TypeIds;
 
 import lombok.AccessLevel;
+import lombok.Singular.NullCollectionBehavior;
 import lombok.core.LombokImmutableList;
 import lombok.core.SpiLoadUtil;
 import lombok.core.TypeLibrary;
 import lombok.core.configuration.CheckerFrameworkVersion;
+import lombok.eclipse.Eclipse;
 import lombok.eclipse.EclipseNode;
 
 public class EclipseSingularsRecipes {
@@ -126,13 +134,14 @@ public class EclipseSingularsRecipes {
 		private final List<TypeReference> typeArgs;
 		private final String targetFqn;
 		private final EclipseSingularizer singularizer;
+		private final NullCollectionBehavior nullCollectionBehavior;
 		private final ASTNode source;
 		
-		public SingularData(EclipseNode annotation, char[] singularName, char[] pluralName, List<TypeReference> typeArgs, String targetFqn, EclipseSingularizer singularizer, ASTNode source) {
-			this(annotation, singularName, pluralName, typeArgs, targetFqn, singularizer, source, new char[0]);
+		public SingularData(EclipseNode annotation, char[] singularName, char[] pluralName, List<TypeReference> typeArgs, String targetFqn, EclipseSingularizer singularizer, ASTNode source, NullCollectionBehavior nullCollectionBehavior) {
+			this(annotation, singularName, pluralName, typeArgs, targetFqn, singularizer, source, nullCollectionBehavior, new char[0]);
 		}
 		
-		public SingularData(EclipseNode annotation, char[] singularName, char[] pluralName, List<TypeReference> typeArgs, String targetFqn, EclipseSingularizer singularizer, ASTNode source, char[] setterPrefix) {
+		public SingularData(EclipseNode annotation, char[] singularName, char[] pluralName, List<TypeReference> typeArgs, String targetFqn, EclipseSingularizer singularizer, ASTNode source, NullCollectionBehavior nullCollectionBehavior, char[] setterPrefix) {
 			this.annotation = annotation;
 			this.singularName = singularName;
 			this.pluralName = pluralName;
@@ -140,6 +149,7 @@ public class EclipseSingularsRecipes {
 			this.targetFqn = targetFqn;
 			this.singularizer = singularizer;
 			this.source = source;
+			this.nullCollectionBehavior = nullCollectionBehavior;
 			this.setterPrefix = setterPrefix;
 		}
 		
@@ -187,6 +197,10 @@ public class EclipseSingularsRecipes {
 			return singularizer;
 		}
 		
+		public NullCollectionBehavior getNullCollectionBehavior() {
+			return nullCollectionBehavior;
+		}
+		
 		public String getTargetSimpleType() {
 			int idx = targetFqn.lastIndexOf(".");
 			return idx == -1 ? targetFqn : targetFqn.substring(idx + 1);
@@ -423,6 +437,45 @@ public class EclipseSingularsRecipes {
 			}
 		}
 		
+		protected void nullBehaviorize(SingularData data, List<Statement> statements) {
+			NullCollectionBehavior behavior = data.getNullCollectionBehavior();
+			
+			if (behavior == NullCollectionBehavior.IGNORE) {
+				Expression isNotNull = new EqualExpression(new SingleNameReference(data.getPluralName(), 0L), new NullLiteral(0, 0), OperatorIds.NOT_EQUAL);
+				Block b = new Block(0);
+				b.statements = statements.toArray(new Statement[statements.size()]);
+				statements.clear();
+				statements.add(new IfStatement(isNotNull, b, 0, 0));
+				return;
+			}
+			
+			String exceptionTypeStr = behavior.getExceptionType();
+			StringLiteral message = new StringLiteral(behavior.toExceptionMessage(new String(data.getPluralName())).toCharArray(), 0, 0, 0);
+			if (exceptionTypeStr != null) {
+				Expression isNull = new EqualExpression(new SingleNameReference(data.getPluralName(), 0L), new NullLiteral(0, 0), OperatorIds.EQUAL_EQUAL);
+				int partCount = 1;
+				for (int i = 0; i < exceptionTypeStr.length(); i++) if (exceptionTypeStr.charAt(i) == '.') partCount++;
+				long[] ps = new long[partCount];
+				Arrays.fill(ps, 0L);
+				AllocationExpression alloc = new AllocationExpression();
+				alloc.type = new QualifiedTypeReference(Eclipse.fromQualifiedName(exceptionTypeStr), ps);
+				alloc.arguments = new Expression[] {message};
+				Statement t = new ThrowStatement(alloc, 0, 0);
+				statements.add(0, new IfStatement(isNull, t, 0, 0));
+				return;
+			}
+			
+			MessageSend invoke = new MessageSend();
+			LombokImmutableList<String> method = behavior.getMethod();
+			char[][] utilityTypeName = new char[method.size() - 1][];
+			for (int i = 0; i < method.size() - 1; i++) utilityTypeName[i] = method.get(i).toCharArray();
+			
+			invoke.receiver = new QualifiedNameReference(utilityTypeName, new long[method.size() - 1], 0, 0);
+			invoke.selector = method.get(method.size() - 1).toCharArray();
+			invoke.arguments = new Expression[] {new SingleNameReference(data.getPluralName(), 0L), message};
+			statements.add(0, invoke);
+		}
+		
 		protected abstract char[][] getEmptyMakerReceiver(String targetFqn);
 		protected abstract char[] getEmptyMakerSelector(String targetFqn);
 	}
diff --git a/src/core/lombok/eclipse/handlers/HandleBuilder.java b/src/core/lombok/eclipse/handlers/HandleBuilder.java
index bb031ebc..578fa2a3 100755
--- a/src/core/lombok/eclipse/handlers/HandleBuilder.java
+++ b/src/core/lombok/eclipse/handlers/HandleBuilder.java
@@ -79,6 +79,7 @@ import org.mangosdk.spi.ProviderFor;
 import lombok.AccessLevel;
 import lombok.Builder;
 import lombok.Builder.ObtainVia;
+import lombok.Singular.NullCollectionBehavior;
 import lombok.ConfigurationKeys;
 import lombok.Singular;
 import lombok.ToString;
@@ -992,7 +993,8 @@ public class HandleBuilder extends EclipseAnnotationHandler<Builder> {
 			if (!annotationTypeMatches(Singular.class, child)) continue;
 			char[] pluralName = node.getKind() == Kind.FIELD ? removePrefixFromField(node) : ((AbstractVariableDeclaration) node.get()).name;
 			AnnotationValues<Singular> ann = createAnnotation(Singular.class, child);
-			String explicitSingular = ann.getInstance().value();
+			Singular singularInstance = ann.getInstance();
+			String explicitSingular = singularInstance.value();
 			if (explicitSingular.isEmpty()) {
 				if (Boolean.FALSE.equals(node.getAst().readConfiguration(ConfigurationKeys.SINGULAR_AUTO))) {
 					node.addError("The singular must be specified explicitly (e.g. @Singular(\"task\")) because auto singularization is disabled.");
@@ -1034,9 +1036,21 @@ public class HandleBuilder extends EclipseAnnotationHandler<Builder> {
 				return null;
 			}
 			
-			return new SingularData(child, singularName, pluralName, typeArgs == null ? Collections.<TypeReference>emptyList() : Arrays.asList(typeArgs), targetFqn, singularizer, source, setterPrefix.toCharArray());
+			NullCollectionBehavior behavior = getNullBehaviorFor(ann, singularInstance, node);
+			return new SingularData(child, singularName, pluralName, typeArgs == null ? Collections.<TypeReference>emptyList() : Arrays.asList(typeArgs), targetFqn, singularizer, source, behavior, setterPrefix.toCharArray());
 		}
 		
 		return null;
 	}
+	
+	static NullCollectionBehavior getNullBehaviorFor(AnnotationValues<Singular> ann, Singular singularInstance, EclipseNode node) {
+		NullCollectionBehavior behavior;
+		if (ann.isExplicit("nullBehavior")) {
+			behavior = singularInstance.nullBehavior();
+		} else {
+			behavior = node.getAst().readConfiguration(ConfigurationKeys.SINGULAR_NULL_COLLECTIONS);
+		}
+		if (behavior == null) return NullCollectionBehavior.NULL_POINTER_EXCEPTION;
+		return behavior;
+	}
 }
diff --git a/src/core/lombok/eclipse/handlers/HandleSuperBuilder.java b/src/core/lombok/eclipse/handlers/HandleSuperBuilder.java
index 3a2e59f7..4b450a07 100755
--- a/src/core/lombok/eclipse/handlers/HandleSuperBuilder.java
+++ b/src/core/lombok/eclipse/handlers/HandleSuperBuilder.java
@@ -79,6 +79,7 @@ import org.mangosdk.spi.ProviderFor;
 import lombok.AccessLevel;
 import lombok.Builder;
 import lombok.Builder.ObtainVia;
+import lombok.Singular.NullCollectionBehavior;
 import lombok.ConfigurationKeys;
 import lombok.Singular;
 import lombok.ToString;
@@ -1000,7 +1001,8 @@ public class HandleSuperBuilder extends EclipseAnnotationHandler<SuperBuilder> {
 			
 			char[] pluralName = node.getKind() == Kind.FIELD ? removePrefixFromField(node) : ((AbstractVariableDeclaration) node.get()).name;
 			AnnotationValues<Singular> ann = createAnnotation(Singular.class, child);
-			String explicitSingular = ann.getInstance().value();
+			Singular singularInstance = ann.getInstance();
+			String explicitSingular = singularInstance.value();
 			if (explicitSingular.isEmpty()) {
 				if (Boolean.FALSE.equals(node.getAst().readConfiguration(ConfigurationKeys.SINGULAR_AUTO))) {
 					node.addError("The singular must be specified explicitly (e.g. @Singular(\"task\")) because auto singularization is disabled.");
@@ -1042,7 +1044,8 @@ public class HandleSuperBuilder extends EclipseAnnotationHandler<SuperBuilder> {
 				return null;
 			}
 			
-			return new SingularData(child, singularName, pluralName, typeArgs == null ? Collections.<TypeReference>emptyList() : Arrays.asList(typeArgs), targetFqn, singularizer, source);
+			NullCollectionBehavior behavior = HandleBuilder.getNullBehaviorFor(ann, singularInstance, node);
+			return new SingularData(child, singularName, pluralName, typeArgs == null ? Collections.<TypeReference>emptyList() : Arrays.asList(typeArgs), targetFqn, singularizer, source, behavior);
 		}
 		
 		return null;
diff --git a/src/core/lombok/eclipse/handlers/singulars/EclipseGuavaSingularizer.java b/src/core/lombok/eclipse/handlers/singulars/EclipseGuavaSingularizer.java
index 8f80d228..b067ad80 100755
--- a/src/core/lombok/eclipse/handlers/singulars/EclipseGuavaSingularizer.java
+++ b/src/core/lombok/eclipse/handlers/singulars/EclipseGuavaSingularizer.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2015-2019 The Project Lombok Authors.
+ * Copyright (C) 2015-2020 The Project Lombok Authors.
  * 
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -195,6 +195,9 @@ abstract class EclipseGuavaSingularizer extends EclipseSingularizer {
 		thisDotFieldDotAddAll.receiver = thisDotField;
 		thisDotFieldDotAddAll.selector = (getAddMethodName() + "All").toCharArray();
 		statements.add(thisDotFieldDotAddAll);
+		
+		nullBehaviorize(data, statements);
+		
 		if (returnStatement != null) statements.add(returnStatement);
 		
 		md.statements = statements.toArray(new Statement[0]);
diff --git a/src/core/lombok/eclipse/handlers/singulars/EclipseJavaUtilListSetSingularizer.java b/src/core/lombok/eclipse/handlers/singulars/EclipseJavaUtilListSetSingularizer.java
index e3a99008..ba447397 100755
--- a/src/core/lombok/eclipse/handlers/singulars/EclipseJavaUtilListSetSingularizer.java
+++ b/src/core/lombok/eclipse/handlers/singulars/EclipseJavaUtilListSetSingularizer.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2015-2019 The Project Lombok Authors.
+ * Copyright (C) 2015-2020 The Project Lombok Authors.
  * 
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -173,6 +173,8 @@ abstract class EclipseJavaUtilListSetSingularizer extends EclipseJavaUtilSingula
 		thisDotFieldDotAddAll.receiver = thisDotField;
 		thisDotFieldDotAddAll.selector = "addAll".toCharArray();
 		statements.add(thisDotFieldDotAddAll);
+		
+		nullBehaviorize(data, statements);
 		if (returnStatement != null) statements.add(returnStatement);
 		
 		md.statements = statements.toArray(new Statement[0]);
diff --git a/src/core/lombok/eclipse/handlers/singulars/EclipseJavaUtilMapSingularizer.java b/src/core/lombok/eclipse/handlers/singulars/EclipseJavaUtilMapSingularizer.java
index b0223c50..e91c6616 100755
--- a/src/core/lombok/eclipse/handlers/singulars/EclipseJavaUtilMapSingularizer.java
+++ b/src/core/lombok/eclipse/handlers/singulars/EclipseJavaUtilMapSingularizer.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2015-2019 The Project Lombok Authors.
+ * Copyright (C) 2015-2020 The Project Lombok Authors.
  * 
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -305,6 +305,9 @@ public class EclipseJavaUtilMapSingularizer extends EclipseJavaUtilSingularizer
 		forEachContent.statements = new Statement[] {addKey, addValue};
 		forEach.action = forEachContent;
 		statements.add(forEach);
+		
+		nullBehaviorize(data, statements);
+		
 		if (returnStatement != null) statements.add(returnStatement);
 		
 		md.statements = statements.toArray(new Statement[0]);
diff --git a/src/core/lombok/javac/handlers/HandleBuilder.java b/src/core/lombok/javac/handlers/HandleBuilder.java
index 5fc3957b..75f3de2c 100644
--- a/src/core/lombok/javac/handlers/HandleBuilder.java
+++ b/src/core/lombok/javac/handlers/HandleBuilder.java
@@ -61,6 +61,7 @@ import lombok.Builder;
 import lombok.Builder.ObtainVia;
 import lombok.ConfigurationKeys;
 import lombok.Singular;
+import lombok.Singular.NullCollectionBehavior;
 import lombok.ToString;
 import lombok.core.AST.Kind;
 import lombok.core.AnnotationValues;
@@ -869,8 +870,9 @@ public class HandleBuilder extends JavacAnnotationHandler<Builder> {
 			if (!annotationTypeMatches(Singular.class, child)) continue;
 			Name pluralName = node.getKind() == Kind.FIELD ? removePrefixFromField(node) : ((JCVariableDecl) node.get()).name;
 			AnnotationValues<Singular> ann = createAnnotation(Singular.class, child);
+			Singular singularInstance = ann.getInstance();
 			deleteAnnotationIfNeccessary(child, Singular.class);
-			String explicitSingular = ann.getInstance().value();
+			String explicitSingular = singularInstance.value();
 			if (explicitSingular.isEmpty()) {
 				if (Boolean.FALSE.equals(node.getAst().readConfiguration(ConfigurationKeys.SINGULAR_AUTO))) {
 					node.addError("The singular must be specified explicitly (e.g. @Singular(\"task\")) because auto singularization is disabled.");
@@ -906,9 +908,22 @@ public class HandleBuilder extends JavacAnnotationHandler<Builder> {
 				return null;
 			}
 			
-			return new SingularData(child, singularName, pluralName, typeArgs, targetFqn, singularizer, setterPrefix);
+			NullCollectionBehavior behavior = getNullBehaviorFor(ann, singularInstance, node);
+			
+			return new SingularData(child, singularName, pluralName, typeArgs, targetFqn, singularizer, behavior, setterPrefix);
 		}
 		
 		return null;
 	}
+	
+	static NullCollectionBehavior getNullBehaviorFor(AnnotationValues<Singular> ann, Singular singularInstance, JavacNode node) {
+		NullCollectionBehavior behavior;
+		if (ann.isExplicit("nullBehavior")) {
+			behavior = singularInstance.nullBehavior();
+		} else {
+			behavior = node.getAst().readConfiguration(ConfigurationKeys.SINGULAR_NULL_COLLECTIONS);
+		}
+		if (behavior == null) return NullCollectionBehavior.NULL_POINTER_EXCEPTION;
+		return behavior;
+	}
 }
diff --git a/src/core/lombok/javac/handlers/HandleSuperBuilder.java b/src/core/lombok/javac/handlers/HandleSuperBuilder.java
index b3002946..692ee60b 100644
--- a/src/core/lombok/javac/handlers/HandleSuperBuilder.java
+++ b/src/core/lombok/javac/handlers/HandleSuperBuilder.java
@@ -59,6 +59,7 @@ import com.sun.tools.javac.util.Name;
 import lombok.AccessLevel;
 import lombok.Builder;
 import lombok.Builder.ObtainVia;
+import lombok.Singular.NullCollectionBehavior;
 import lombok.ConfigurationKeys;
 import lombok.Singular;
 import lombok.ToString;
@@ -939,8 +940,9 @@ public class HandleSuperBuilder extends JavacAnnotationHandler<SuperBuilder> {
 			if (!annotationTypeMatches(Singular.class, child)) continue;
 			Name pluralName = node.getKind() == Kind.FIELD ? removePrefixFromField(node) : ((JCVariableDecl) node.get()).name;
 			AnnotationValues<Singular> ann = createAnnotation(Singular.class, child);
+			Singular singularInstance = ann.getInstance();
 			deleteAnnotationIfNeccessary(child, Singular.class);
-			String explicitSingular = ann.getInstance().value();
+			String explicitSingular = singularInstance.value();
 			if (explicitSingular.isEmpty()) {
 				if (Boolean.FALSE.equals(node.getAst().readConfiguration(ConfigurationKeys.SINGULAR_AUTO))) {
 					node.addError("The singular must be specified explicitly (e.g. @Singular(\"task\")) because auto singularization is disabled.");
@@ -974,7 +976,8 @@ public class HandleSuperBuilder extends JavacAnnotationHandler<SuperBuilder> {
 				return null;
 			}
 			
-			return new SingularData(child, singularName, pluralName, typeArgs, targetFqn, singularizer);
+			NullCollectionBehavior behavior = HandleBuilder.getNullBehaviorFor(ann, singularInstance, node);
+			return new SingularData(child, singularName, pluralName, typeArgs, targetFqn, singularizer, behavior);
 		}
 		
 		return null;
diff --git a/src/core/lombok/javac/handlers/JavacSingularsRecipes.java b/src/core/lombok/javac/handlers/JavacSingularsRecipes.java
index c1e6edd8..a5d4a295 100644
--- a/src/core/lombok/javac/handlers/JavacSingularsRecipes.java
+++ b/src/core/lombok/javac/handlers/JavacSingularsRecipes.java
@@ -24,33 +24,24 @@ package lombok.javac.handlers;
 import static lombok.javac.Javac.*;
 import static lombok.javac.handlers.JavacHandlerUtil.*;
 
-import com.sun.tools.javac.tree.JCTree.JCBlock;
-import com.sun.tools.javac.tree.JCTree.JCTypeParameter;
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 
-import lombok.AccessLevel;
-import lombok.ConfigurationKeys;
-import lombok.core.LombokImmutableList;
-import lombok.core.SpiLoadUtil;
-import lombok.core.TypeLibrary;
-import lombok.core.configuration.CheckerFrameworkVersion;
-import lombok.core.handlers.HandlerUtil;
-import lombok.javac.JavacNode;
-import lombok.javac.JavacTreeMaker;
-
 import com.sun.source.tree.Tree.Kind;
 import com.sun.tools.javac.code.BoundKind;
 import com.sun.tools.javac.code.Flags;
 import com.sun.tools.javac.tree.JCTree;
 import com.sun.tools.javac.tree.JCTree.JCAnnotation;
+import com.sun.tools.javac.tree.JCTree.JCBlock;
 import com.sun.tools.javac.tree.JCTree.JCExpression;
+import com.sun.tools.javac.tree.JCTree.JCLiteral;
 import com.sun.tools.javac.tree.JCTree.JCMethodDecl;
 import com.sun.tools.javac.tree.JCTree.JCModifiers;
 import com.sun.tools.javac.tree.JCTree.JCStatement;
+import com.sun.tools.javac.tree.JCTree.JCTypeParameter;
 import com.sun.tools.javac.tree.JCTree.JCVariableDecl;
 import com.sun.tools.javac.tree.JCTree.JCWildcard;
 import com.sun.tools.javac.util.Context;
@@ -58,6 +49,17 @@ import com.sun.tools.javac.util.List;
 import com.sun.tools.javac.util.ListBuffer;
 import com.sun.tools.javac.util.Name;
 
+import lombok.AccessLevel;
+import lombok.ConfigurationKeys;
+import lombok.Singular.NullCollectionBehavior;
+import lombok.core.LombokImmutableList;
+import lombok.core.SpiLoadUtil;
+import lombok.core.TypeLibrary;
+import lombok.core.configuration.CheckerFrameworkVersion;
+import lombok.core.handlers.HandlerUtil;
+import lombok.javac.JavacNode;
+import lombok.javac.JavacTreeMaker;
+
 public class JavacSingularsRecipes {
 	public interface ExpressionMaker {
 		JCExpression make();
@@ -120,12 +122,13 @@ public class JavacSingularsRecipes {
 		private final String targetFqn;
 		private final JavacSingularizer singularizer;
 		private final String setterPrefix;
+		private final NullCollectionBehavior nullCollectionBehavior;
 		
-		public SingularData(JavacNode annotation, Name singularName, Name pluralName, List<JCExpression> typeArgs, String targetFqn, JavacSingularizer singularizer) {
-			this(annotation, singularName, pluralName, typeArgs, targetFqn, singularizer, "");
+		public SingularData(JavacNode annotation, Name singularName, Name pluralName, List<JCExpression> typeArgs, String targetFqn, JavacSingularizer singularizer, NullCollectionBehavior nullCollectionBehavior) {
+			this(annotation, singularName, pluralName, typeArgs, targetFqn, singularizer, nullCollectionBehavior, "");
 		}
 		
-		public SingularData(JavacNode annotation, Name singularName, Name pluralName, List<JCExpression> typeArgs, String targetFqn, JavacSingularizer singularizer, String setterPrefix) {
+		public SingularData(JavacNode annotation, Name singularName, Name pluralName, List<JCExpression> typeArgs, String targetFqn, JavacSingularizer singularizer, NullCollectionBehavior nullCollectionBehavior, String setterPrefix) {
 			this.annotation = annotation;
 			this.singularName = singularName;
 			this.pluralName = pluralName;
@@ -133,6 +136,7 @@ public class JavacSingularsRecipes {
 			this.targetFqn = targetFqn;
 			this.singularizer = singularizer;
 			this.setterPrefix = setterPrefix;
+			this.nullCollectionBehavior = nullCollectionBehavior;
 		}
 		
 		public JavacNode getAnnotation() {
@@ -163,6 +167,10 @@ public class JavacSingularsRecipes {
 			return singularizer;
 		}
 		
+		public NullCollectionBehavior getNullCollectionBehavior() {
+			return nullCollectionBehavior;
+		}
+		
 		public String getTargetSimpleType() {
 			int idx = targetFqn.lastIndexOf(".");
 			return idx == -1 ? targetFqn : targetFqn.substring(idx + 1);
@@ -320,6 +328,7 @@ public class JavacSingularsRecipes {
 		
 		private void generatePluralMethod(CheckerFrameworkVersion cfv, boolean deprecate, JavacTreeMaker maker, JCExpression returnType, JCStatement returnStatement, SingularData data, JavacNode builderType, JCTree source, boolean fluent, AccessLevel access) {
 			ListBuffer<JCStatement> statements = generatePluralMethodStatements(maker, data, builderType, source);
+			
 			Name name = data.getPluralName();
 			String setterPrefix = data.getSetterPrefix();
 			if (setterPrefix.isEmpty() && !fluent) setterPrefix = getAddMethodName() + "All";
@@ -329,13 +338,40 @@ public class JavacSingularsRecipes {
 			long paramFlags = JavacHandlerUtil.addFinalIfNeeded(Flags.PARAMETER, builderType.getContext());
 			JCVariableDecl param = maker.VarDef(maker.Modifiers(paramFlags), data.getPluralName(), paramType, null);
 			statements.prepend(createConstructBuilderVarIfNeeded(maker, data, builderType, source));
+			
+			NullCollectionBehavior behavior = data.getNullCollectionBehavior();
+			
+			if (behavior == NullCollectionBehavior.IGNORE) {
+				JCExpression incomingIsNotNull = maker.Binary(CTC_NOT_EQUAL, maker.Ident(data.getPluralName()), maker.Literal(CTC_BOT, null));
+				JCStatement onNotNull = maker.Block(0, statements.toList());
+				statements = new ListBuffer<JCStatement>();
+				statements.add(maker.If(incomingIsNotNull, onNotNull, null));
+			} else {
+				JCLiteral message = maker.Literal(behavior.toExceptionMessage(data.getPluralName().toString()));
+				if (behavior.getExceptionType() != null) {
+					JCExpression incomingIsNull = maker.Binary(CTC_EQUAL, maker.Ident(data.getPluralName()), maker.Literal(CTC_BOT, null));
+					JCExpression exType = genTypeRef(builderType, behavior.getExceptionType());
+					JCExpression exception = maker.NewClass(null, List.<JCExpression>nil(), exType, List.<JCExpression>of(message), null);
+					JCStatement onNull = maker.Throw(exception);
+					statements.prepend(maker.If(incomingIsNull, onNull, null));
+				} else {
+					LombokImmutableList<String> method = behavior.getMethod();
+					JCExpression invoke = maker.Apply(List.<JCExpression>nil(), chainDots(builderType, method), List.of(maker.Ident(data.getPluralName()), message));
+					statements.prepend(maker.Exec(invoke));
+				}
+			}
+			
 			finishAndInjectMethod(cfv, maker, returnType, returnStatement, data, builderType, source, deprecate, statements, name, List.of(param), access);
 		}
 		
 		protected ListBuffer<JCStatement> generatePluralMethodStatements(JavacTreeMaker maker, SingularData data, JavacNode builderType, JCTree source) {
+			ListBuffer<JCStatement> statements = new ListBuffer<JCStatement>();
+			
 			JCExpression thisDotFieldDotAdd = chainDots(builderType, "this", data.getPluralName().toString(), getAddMethodName() + "All");
 			JCExpression invokeAdd = maker.Apply(List.<JCExpression>nil(), thisDotFieldDotAdd, List.<JCExpression>of(maker.Ident(data.getPluralName())));
-			return new ListBuffer<JCStatement>().append(maker.Exec(invokeAdd));
+			statements.append(maker.Exec(invokeAdd));
+			
+			return statements;
 		}
 		
 		protected abstract JCExpression getPluralMethodParamType(JavacNode builderType);
diff --git a/test/core/src/lombok/DirectoryRunner.java b/test/core/src/lombok/DirectoryRunner.java
index 116b9d94..b8b1da43 100644
--- a/test/core/src/lombok/DirectoryRunner.java
+++ b/test/core/src/lombok/DirectoryRunner.java
@@ -77,7 +77,7 @@ public class DirectoryRunner extends Runner {
 			return true;
 		}
 		
-		public abstract boolean expectChanges(); 
+		public abstract boolean expectChanges();
 	}
 	
 	private static final FileFilter JAVA_FILE_FILTER = new FileFilter() {
diff --git a/test/transform/resource/after-delombok/BuilderDefaultsWarnings.java b/test/transform/resource/after-delombok/BuilderDefaultsWarnings.java
index 4df98158..04cd3bbb 100644
--- a/test/transform/resource/after-delombok/BuilderDefaultsWarnings.java
+++ b/test/transform/resource/after-delombok/BuilderDefaultsWarnings.java
@@ -38,6 +38,7 @@ public class BuilderDefaultsWarnings {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderDefaultsWarnings.BuilderDefaultsWarningsBuilder items(final java.util.Collection<? extends String> items) {
+			if (items == null) throw new java.lang.NullPointerException("items cannot be null");
 			if (this.items == null) this.items = new java.util.ArrayList<String>();
 			this.items.addAll(items);
 			return this;
diff --git a/test/transform/resource/after-delombok/BuilderSingularAnnotatedTypes.java b/test/transform/resource/after-delombok/BuilderSingularAnnotatedTypes.java
index 6bd3390c..4cc247ef 100644
--- a/test/transform/resource/after-delombok/BuilderSingularAnnotatedTypes.java
+++ b/test/transform/resource/after-delombok/BuilderSingularAnnotatedTypes.java
@@ -36,6 +36,7 @@ class BuilderSingularAnnotatedTypes {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularAnnotatedTypes.BuilderSingularAnnotatedTypesBuilder foos(final java.util.Collection<? extends @MyAnnotation @NonNull String> foos) {
+			if (foos == null) throw new java.lang.NullPointerException("foos cannot be null");
 			if (this.foos == null) this.foos = new java.util.ArrayList<@MyAnnotation @NonNull String>();
 			this.foos.addAll(foos);
 			return this;
@@ -63,6 +64,7 @@ class BuilderSingularAnnotatedTypes {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularAnnotatedTypes.BuilderSingularAnnotatedTypesBuilder bars(final java.util.Map<? extends @MyAnnotation @NonNull String, ? extends @MyAnnotation @NonNull Integer> bars) {
+			if (bars == null) throw new java.lang.NullPointerException("bars cannot be null");
 			if (this.bars$key == null) {
 				this.bars$key = new java.util.ArrayList<@MyAnnotation @NonNull String>();
 				this.bars$value = new java.util.ArrayList<@MyAnnotation @NonNull Integer>();
diff --git a/test/transform/resource/after-delombok/BuilderSingularAnnotatedTypesWithSetterPrefix.java b/test/transform/resource/after-delombok/BuilderSingularAnnotatedTypesWithSetterPrefix.java
index d1047567..90cc5570 100644
--- a/test/transform/resource/after-delombok/BuilderSingularAnnotatedTypesWithSetterPrefix.java
+++ b/test/transform/resource/after-delombok/BuilderSingularAnnotatedTypesWithSetterPrefix.java
@@ -36,6 +36,7 @@ class BuilderSingularAnnotatedTypesWithSetterPrefix {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularAnnotatedTypesWithSetterPrefix.BuilderSingularAnnotatedTypesWithSetterPrefixBuilder withFoos(final java.util.Collection<? extends @MyAnnotation @NonNull String> foos) {
+			if (foos == null) throw new java.lang.NullPointerException("foos cannot be null");
 			if (this.foos == null) this.foos = new java.util.ArrayList<@MyAnnotation @NonNull String>();
 			this.foos.addAll(foos);
 			return this;
@@ -63,6 +64,7 @@ class BuilderSingularAnnotatedTypesWithSetterPrefix {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularAnnotatedTypesWithSetterPrefix.BuilderSingularAnnotatedTypesWithSetterPrefixBuilder withBars(final java.util.Map<? extends @MyAnnotation @NonNull String, ? extends @MyAnnotation @NonNull Integer> bars) {
+			if (bars == null) throw new java.lang.NullPointerException("bars cannot be null");
 			if (this.bars$key == null) {
 				this.bars$key = new java.util.ArrayList<@MyAnnotation @NonNull String>();
 				this.bars$value = new java.util.ArrayList<@MyAnnotation @NonNull Integer>();
diff --git a/test/transform/resource/after-delombok/BuilderSingularGuavaListsSets.java b/test/transform/resource/after-delombok/BuilderSingularGuavaListsSets.java
index b6fb5732..650ab2fd 100644
--- a/test/transform/resource/after-delombok/BuilderSingularGuavaListsSets.java
+++ b/test/transform/resource/after-delombok/BuilderSingularGuavaListsSets.java
@@ -41,6 +41,7 @@ class BuilderSingularGuavaListsSets<T> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularGuavaListsSets.BuilderSingularGuavaListsSetsBuilder<T> cards(final java.lang.Iterable<? extends T> cards) {
+			if (cards == null) throw new java.lang.NullPointerException("cards cannot be null");
 			if (this.cards == null) this.cards = com.google.common.collect.ImmutableList.builder();
 			this.cards.addAll(cards);
 			return this;
@@ -58,6 +59,7 @@ class BuilderSingularGuavaListsSets<T> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularGuavaListsSets.BuilderSingularGuavaListsSetsBuilder<T> frogs(final java.lang.Iterable<? extends Number> frogs) {
+			if (frogs == null) throw new java.lang.NullPointerException("frogs cannot be null");
 			if (this.frogs == null) this.frogs = com.google.common.collect.ImmutableList.builder();
 			this.frogs.addAll(frogs);
 			return this;
@@ -75,6 +77,7 @@ class BuilderSingularGuavaListsSets<T> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularGuavaListsSets.BuilderSingularGuavaListsSetsBuilder<T> rawSet(final java.lang.Iterable<?> rawSet) {
+			if (rawSet == null) throw new java.lang.NullPointerException("rawSet cannot be null");
 			if (this.rawSet == null) this.rawSet = com.google.common.collect.ImmutableSet.builder();
 			this.rawSet.addAll(rawSet);
 			return this;
@@ -92,6 +95,7 @@ class BuilderSingularGuavaListsSets<T> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularGuavaListsSets.BuilderSingularGuavaListsSetsBuilder<T> passes(final java.lang.Iterable<? extends String> passes) {
+			if (passes == null) throw new java.lang.NullPointerException("passes cannot be null");
 			if (this.passes == null) this.passes = com.google.common.collect.ImmutableSortedSet.naturalOrder();
 			this.passes.addAll(passes);
 			return this;
@@ -109,6 +113,7 @@ class BuilderSingularGuavaListsSets<T> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularGuavaListsSets.BuilderSingularGuavaListsSetsBuilder<T> users(final com.google.common.collect.Table<? extends Number, ? extends Number, ? extends String> users) {
+			if (users == null) throw new java.lang.NullPointerException("users cannot be null");
 			if (this.users == null) this.users = com.google.common.collect.ImmutableTable.builder();
 			this.users.putAll(users);
 			return this;
diff --git a/test/transform/resource/after-delombok/BuilderSingularGuavaMaps.java b/test/transform/resource/after-delombok/BuilderSingularGuavaMaps.java
index a6043475..6af1bf8d 100644
--- a/test/transform/resource/after-delombok/BuilderSingularGuavaMaps.java
+++ b/test/transform/resource/after-delombok/BuilderSingularGuavaMaps.java
@@ -31,6 +31,7 @@ class BuilderSingularGuavaMaps<K, V> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularGuavaMaps.BuilderSingularGuavaMapsBuilder<K, V> battleaxes(final java.util.Map<? extends K, ? extends V> battleaxes) {
+			if (battleaxes == null) throw new java.lang.NullPointerException("battleaxes cannot be null");
 			if (this.battleaxes == null) this.battleaxes = com.google.common.collect.ImmutableMap.builder();
 			this.battleaxes.putAll(battleaxes);
 			return this;
@@ -48,6 +49,7 @@ class BuilderSingularGuavaMaps<K, V> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularGuavaMaps.BuilderSingularGuavaMapsBuilder<K, V> vertices(final java.util.Map<? extends Integer, ? extends V> vertices) {
+			if (vertices == null) throw new java.lang.NullPointerException("vertices cannot be null");
 			if (this.vertices == null) this.vertices = com.google.common.collect.ImmutableSortedMap.naturalOrder();
 			this.vertices.putAll(vertices);
 			return this;
@@ -65,6 +67,7 @@ class BuilderSingularGuavaMaps<K, V> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularGuavaMaps.BuilderSingularGuavaMapsBuilder<K, V> rawMap(final java.util.Map<?, ?> rawMap) {
+			if (rawMap == null) throw new java.lang.NullPointerException("rawMap cannot be null");
 			if (this.rawMap == null) this.rawMap = com.google.common.collect.ImmutableBiMap.builder();
 			this.rawMap.putAll(rawMap);
 			return this;
diff --git a/test/transform/resource/after-delombok/BuilderSingularLists.java b/test/transform/resource/after-delombok/BuilderSingularLists.java
index 971a2851..43eb7702 100644
--- a/test/transform/resource/after-delombok/BuilderSingularLists.java
+++ b/test/transform/resource/after-delombok/BuilderSingularLists.java
@@ -30,6 +30,7 @@ class BuilderSingularLists<T> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularLists.BuilderSingularListsBuilder<T> children(final java.util.Collection<? extends T> children) {
+			if (children == null) throw new java.lang.NullPointerException("children cannot be null");
 			if (this.children == null) this.children = new java.util.ArrayList<T>();
 			this.children.addAll(children);
 			return this;
@@ -47,6 +48,7 @@ class BuilderSingularLists<T> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularLists.BuilderSingularListsBuilder<T> scarves(final java.util.Collection<? extends Number> scarves) {
+			if (scarves == null) throw new java.lang.NullPointerException("scarves cannot be null");
 			if (this.scarves == null) this.scarves = new java.util.ArrayList<Number>();
 			this.scarves.addAll(scarves);
 			return this;
@@ -64,6 +66,7 @@ class BuilderSingularLists<T> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularLists.BuilderSingularListsBuilder<T> rawList(final java.util.Collection<?> rawList) {
+			if (rawList == null) throw new java.lang.NullPointerException("rawList cannot be null");
 			if (this.rawList == null) this.rawList = new java.util.ArrayList<java.lang.Object>();
 			this.rawList.addAll(rawList);
 			return this;
diff --git a/test/transform/resource/after-delombok/BuilderSingularMaps.java b/test/transform/resource/after-delombok/BuilderSingularMaps.java
index 240a6e3b..d10dd090 100644
--- a/test/transform/resource/after-delombok/BuilderSingularMaps.java
+++ b/test/transform/resource/after-delombok/BuilderSingularMaps.java
@@ -46,6 +46,7 @@ class BuilderSingularMaps<K, V> {
 		}
 		@SuppressWarnings("all")
 		public BuilderSingularMaps.BuilderSingularMapsBuilder<K, V> women(java.util.Map<? extends K, ? extends V> women) {
+			if (women == null) throw new NullPointerException("women cannot be null");
 			if (this.women$key == null) {
 				this.women$key = new java.util.ArrayList<K>();
 				this.women$value = new java.util.ArrayList<V>();
@@ -76,6 +77,7 @@ class BuilderSingularMaps<K, V> {
 		}
 		@SuppressWarnings("all")
 		public BuilderSingularMaps.BuilderSingularMapsBuilder<K, V> men(java.util.Map<? extends K, ? extends Number> men) {
+			if (men == null) throw new NullPointerException("men cannot be null");
 			if (this.men$key == null) {
 				this.men$key = new java.util.ArrayList<K>();
 				this.men$value = new java.util.ArrayList<Number>();
@@ -106,6 +108,7 @@ class BuilderSingularMaps<K, V> {
 		}
 		@SuppressWarnings("all")
 		public BuilderSingularMaps.BuilderSingularMapsBuilder<K, V> rawMap(java.util.Map<?, ?> rawMap) {
+			if (rawMap == null) throw new NullPointerException("rawMap cannot be null");
 			if (this.rawMap$key == null) {
 				this.rawMap$key = new java.util.ArrayList<Object>();
 				this.rawMap$value = new java.util.ArrayList<Object>();
@@ -136,6 +139,7 @@ class BuilderSingularMaps<K, V> {
 		}
 		@SuppressWarnings("all")
 		public BuilderSingularMaps.BuilderSingularMapsBuilder<K, V> stringMap(java.util.Map<? extends String, ? extends V> stringMap) {
+			if (stringMap == null) throw new NullPointerException("stringMap cannot be null");
 			if (this.stringMap$key == null) {
 				this.stringMap$key = new java.util.ArrayList<String>();
 				this.stringMap$value = new java.util.ArrayList<V>();
diff --git a/test/transform/resource/after-delombok/BuilderSingularMapsWithSetterPrefix.java b/test/transform/resource/after-delombok/BuilderSingularMapsWithSetterPrefix.java
index bfc2e750..baa8f311 100644
--- a/test/transform/resource/after-delombok/BuilderSingularMapsWithSetterPrefix.java
+++ b/test/transform/resource/after-delombok/BuilderSingularMapsWithSetterPrefix.java
@@ -46,13 +46,15 @@ class BuilderSingularMapsWithSetterPrefix<K, V> {
 		}
 		@SuppressWarnings("all")
 		public BuilderSingularMapsWithSetterPrefix.BuilderSingularMapsWithSetterPrefixBuilder<K, V> withWomen(java.util.Map<? extends K, ? extends V> women) {
-			if (this.women$key == null) {
-				this.women$key = new java.util.ArrayList<K>();
-				this.women$value = new java.util.ArrayList<V>();
-			}
-			for (java.util.Map.Entry<? extends K, ? extends V> $lombokEntry : women.entrySet()) {
-				this.women$key.add($lombokEntry.getKey());
-				this.women$value.add($lombokEntry.getValue());
+			if (women != null) {
+				if (this.women$key == null) {
+					this.women$key = new java.util.ArrayList<K>();
+					this.women$value = new java.util.ArrayList<V>();
+				}
+				for (java.util.Map.Entry<? extends K, ? extends V> $lombokEntry : women.entrySet()) {
+					this.women$key.add($lombokEntry.getKey());
+					this.women$value.add($lombokEntry.getValue());
+				}
 			}
 			return this;
 		}
@@ -76,13 +78,15 @@ class BuilderSingularMapsWithSetterPrefix<K, V> {
 		}
 		@SuppressWarnings("all")
 		public BuilderSingularMapsWithSetterPrefix.BuilderSingularMapsWithSetterPrefixBuilder<K, V> withMen(java.util.Map<? extends K, ? extends Number> men) {
-			if (this.men$key == null) {
-				this.men$key = new java.util.ArrayList<K>();
-				this.men$value = new java.util.ArrayList<Number>();
-			}
-			for (java.util.Map.Entry<? extends K, ? extends Number> $lombokEntry : men.entrySet()) {
-				this.men$key.add($lombokEntry.getKey());
-				this.men$value.add($lombokEntry.getValue());
+			if (men != null) {
+				if (this.men$key == null) {
+					this.men$key = new java.util.ArrayList<K>();
+					this.men$value = new java.util.ArrayList<Number>();
+				}
+				for (java.util.Map.Entry<? extends K, ? extends Number> $lombokEntry : men.entrySet()) {
+					this.men$key.add($lombokEntry.getKey());
+					this.men$value.add($lombokEntry.getValue());
+				}
 			}
 			return this;
 		}
@@ -106,13 +110,15 @@ class BuilderSingularMapsWithSetterPrefix<K, V> {
 		}
 		@SuppressWarnings("all")
 		public BuilderSingularMapsWithSetterPrefix.BuilderSingularMapsWithSetterPrefixBuilder<K, V> withRawMap(java.util.Map<?, ?> rawMap) {
-			if (this.rawMap$key == null) {
-				this.rawMap$key = new java.util.ArrayList<Object>();
-				this.rawMap$value = new java.util.ArrayList<Object>();
-			}
-			for (java.util.Map.Entry<?, ?> $lombokEntry : rawMap.entrySet()) {
-				this.rawMap$key.add($lombokEntry.getKey());
-				this.rawMap$value.add($lombokEntry.getValue());
+			if (rawMap != null) {
+				if (this.rawMap$key == null) {
+					this.rawMap$key = new java.util.ArrayList<Object>();
+					this.rawMap$value = new java.util.ArrayList<Object>();
+				}
+				for (java.util.Map.Entry<?, ?> $lombokEntry : rawMap.entrySet()) {
+					this.rawMap$key.add($lombokEntry.getKey());
+					this.rawMap$value.add($lombokEntry.getValue());
+				}
 			}
 			return this;
 		}
@@ -136,13 +142,15 @@ class BuilderSingularMapsWithSetterPrefix<K, V> {
 		}
 		@SuppressWarnings("all")
 		public BuilderSingularMapsWithSetterPrefix.BuilderSingularMapsWithSetterPrefixBuilder<K, V> withStringMap(java.util.Map<? extends String, ? extends V> stringMap) {
-			if (this.stringMap$key == null) {
-				this.stringMap$key = new java.util.ArrayList<String>();
-				this.stringMap$value = new java.util.ArrayList<V>();
-			}
-			for (java.util.Map.Entry<? extends String, ? extends V> $lombokEntry : stringMap.entrySet()) {
-				this.stringMap$key.add($lombokEntry.getKey());
-				this.stringMap$value.add($lombokEntry.getValue());
+			if (stringMap != null) {
+				if (this.stringMap$key == null) {
+					this.stringMap$key = new java.util.ArrayList<String>();
+					this.stringMap$value = new java.util.ArrayList<V>();
+				}
+				for (java.util.Map.Entry<? extends String, ? extends V> $lombokEntry : stringMap.entrySet()) {
+					this.stringMap$key.add($lombokEntry.getKey());
+					this.stringMap$value.add($lombokEntry.getValue());
+				}
 			}
 			return this;
 		}
diff --git a/test/transform/resource/after-delombok/BuilderSingularNoAuto.java b/test/transform/resource/after-delombok/BuilderSingularNoAuto.java
index a38effc0..6b2fd5b2 100644
--- a/test/transform/resource/after-delombok/BuilderSingularNoAuto.java
+++ b/test/transform/resource/after-delombok/BuilderSingularNoAuto.java
@@ -28,6 +28,7 @@ class BuilderSingularNoAuto {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularNoAuto.BuilderSingularNoAutoBuilder things(final java.util.Collection<? extends String> things) {
+			if (things == null) throw new java.lang.NullPointerException("things cannot be null");
 			if (this.things == null) this.things = new java.util.ArrayList<String>();
 			this.things.addAll(things);
 			return this;
@@ -45,6 +46,7 @@ class BuilderSingularNoAuto {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularNoAuto.BuilderSingularNoAutoBuilder widgets(final java.util.Collection<? extends String> widgets) {
+			if (widgets == null) throw new java.lang.NullPointerException("widgets cannot be null");
 			if (this.widgets == null) this.widgets = new java.util.ArrayList<String>();
 			this.widgets.addAll(widgets);
 			return this;
@@ -62,6 +64,7 @@ class BuilderSingularNoAuto {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularNoAuto.BuilderSingularNoAutoBuilder items(final java.util.Collection<? extends String> items) {
+			if (items == null) throw new java.lang.NullPointerException("items cannot be null");
 			if (this.items == null) this.items = new java.util.ArrayList<String>();
 			this.items.addAll(items);
 			return this;
diff --git a/test/transform/resource/after-delombok/BuilderSingularNoAutoWithSetterPrefix.java b/test/transform/resource/after-delombok/BuilderSingularNoAutoWithSetterPrefix.java
index 57bef625..a023b82a 100644
--- a/test/transform/resource/after-delombok/BuilderSingularNoAutoWithSetterPrefix.java
+++ b/test/transform/resource/after-delombok/BuilderSingularNoAutoWithSetterPrefix.java
@@ -28,6 +28,7 @@ class BuilderSingularNoAutoWithSetterPrefix {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularNoAutoWithSetterPrefix.BuilderSingularNoAutoWithSetterPrefixBuilder withThings(final java.util.Collection<? extends String> things) {
+			if (things == null) throw new java.lang.NullPointerException("things cannot be null");
 			if (this.things == null) this.things = new java.util.ArrayList<String>();
 			this.things.addAll(things);
 			return this;
@@ -45,6 +46,7 @@ class BuilderSingularNoAutoWithSetterPrefix {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularNoAutoWithSetterPrefix.BuilderSingularNoAutoWithSetterPrefixBuilder withWidgets(final java.util.Collection<? extends String> widgets) {
+			if (widgets == null) throw new java.lang.NullPointerException("widgets cannot be null");
 			if (this.widgets == null) this.widgets = new java.util.ArrayList<String>();
 			this.widgets.addAll(widgets);
 			return this;
@@ -62,6 +64,7 @@ class BuilderSingularNoAutoWithSetterPrefix {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularNoAutoWithSetterPrefix.BuilderSingularNoAutoWithSetterPrefixBuilder withItems(final java.util.Collection<? extends String> items) {
+			if (items == null) throw new java.lang.NullPointerException("items cannot be null");
 			if (this.items == null) this.items = new java.util.ArrayList<String>();
 			this.items.addAll(items);
 			return this;
diff --git a/test/transform/resource/after-delombok/BuilderSingularNullBehavior1.java b/test/transform/resource/after-delombok/BuilderSingularNullBehavior1.java
new file mode 100644
index 00000000..7b4e0a29
--- /dev/null
+++ b/test/transform/resource/after-delombok/BuilderSingularNullBehavior1.java
@@ -0,0 +1,160 @@
+import java.util.List;
+import java.util.Collection;
+import lombok.Singular.NullCollectionBehavior;
+class BuilderSingularNullBehavior1 {
+	private List<String> names;
+	private List<String> locations;
+	private List<String> whatevers;
+	private List<String> doohickeys;
+	@java.lang.SuppressWarnings("all")
+	BuilderSingularNullBehavior1(final List<String> names, final List<String> locations, final List<String> whatevers, final List<String> doohickeys) {
+		this.names = names;
+		this.locations = locations;
+		this.whatevers = whatevers;
+		this.doohickeys = doohickeys;
+	}
+	@java.lang.SuppressWarnings("all")
+	public static class BuilderSingularNullBehavior1Builder {
+		@java.lang.SuppressWarnings("all")
+		private java.util.ArrayList<String> names;
+		@java.lang.SuppressWarnings("all")
+		private java.util.ArrayList<String> locations;
+		@java.lang.SuppressWarnings("all")
+		private java.util.ArrayList<String> whatevers;
+		@java.lang.SuppressWarnings("all")
+		private java.util.ArrayList<String> doohickeys;
+		@java.lang.SuppressWarnings("all")
+		BuilderSingularNullBehavior1Builder() {
+		}
+		@java.lang.SuppressWarnings("all")
+		public BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder name(final String name) {
+			if (this.names == null) this.names = new java.util.ArrayList<String>();
+			this.names.add(name);
+			return this;
+		}
+		@java.lang.SuppressWarnings("all")
+		public BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder names(final java.util.Collection<? extends String> names) {
+			if (names == null) throw new java.lang.NullPointerException("names cannot be null");
+			if (this.names == null) this.names = new java.util.ArrayList<String>();
+			this.names.addAll(names);
+			return this;
+		}
+		@java.lang.SuppressWarnings("all")
+		public BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder clearNames() {
+			if (this.names != null) this.names.clear();
+			return this;
+		}
+		@java.lang.SuppressWarnings("all")
+		public BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder location(final String location) {
+			if (this.locations == null) this.locations = new java.util.ArrayList<String>();
+			this.locations.add(location);
+			return this;
+		}
+		@java.lang.SuppressWarnings("all")
+		public BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder locations(final java.util.Collection<? extends String> locations) {
+			java.util.Objects.requireNonNull(locations, "locations cannot be null");
+			if (this.locations == null) this.locations = new java.util.ArrayList<String>();
+			this.locations.addAll(locations);
+			return this;
+		}
+		@java.lang.SuppressWarnings("all")
+		public BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder clearLocations() {
+			if (this.locations != null) this.locations.clear();
+			return this;
+		}
+		@java.lang.SuppressWarnings("all")
+		public BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder whatever(final String whatever) {
+			if (this.whatevers == null) this.whatevers = new java.util.ArrayList<String>();
+			this.whatevers.add(whatever);
+			return this;
+		}
+		@java.lang.SuppressWarnings("all")
+		public BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder whatevers(final java.util.Collection<? extends String> whatevers) {
+			com.google.common.base.Preconditions.checkNotNull(whatevers, "whatevers cannot be null");
+			if (this.whatevers == null) this.whatevers = new java.util.ArrayList<String>();
+			this.whatevers.addAll(whatevers);
+			return this;
+		}
+		@java.lang.SuppressWarnings("all")
+		public BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder clearWhatevers() {
+			if (this.whatevers != null) this.whatevers.clear();
+			return this;
+		}
+		@java.lang.SuppressWarnings("all")
+		public BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder doohickey(final String doohickey) {
+			if (this.doohickeys == null) this.doohickeys = new java.util.ArrayList<String>();
+			this.doohickeys.add(doohickey);
+			return this;
+		}
+		@java.lang.SuppressWarnings("all")
+		public BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder doohickeys(final java.util.Collection<? extends String> doohickeys) {
+			if (doohickeys != null) {
+				if (this.doohickeys == null) this.doohickeys = new java.util.ArrayList<String>();
+				this.doohickeys.addAll(doohickeys);
+			}
+			return this;
+		}
+		@java.lang.SuppressWarnings("all")
+		public BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder clearDoohickeys() {
+			if (this.doohickeys != null) this.doohickeys.clear();
+			return this;
+		}
+		@java.lang.SuppressWarnings("all")
+		public BuilderSingularNullBehavior1 build() {
+			java.util.List<String> names;
+			switch (this.names == null ? 0 : this.names.size()) {
+			case 0: 
+				names = java.util.Collections.emptyList();
+				break;
+			case 1: 
+				names = java.util.Collections.singletonList(this.names.get(0));
+				break;
+			default: 
+				names = java.util.Collections.unmodifiableList(new java.util.ArrayList<String>(this.names));
+			}
+			java.util.List<String> locations;
+			switch (this.locations == null ? 0 : this.locations.size()) {
+			case 0: 
+				locations = java.util.Collections.emptyList();
+				break;
+			case 1: 
+				locations = java.util.Collections.singletonList(this.locations.get(0));
+				break;
+			default: 
+				locations = java.util.Collections.unmodifiableList(new java.util.ArrayList<String>(this.locations));
+			}
+			java.util.List<String> whatevers;
+			switch (this.whatevers == null ? 0 : this.whatevers.size()) {
+			case 0: 
+				whatevers = java.util.Collections.emptyList();
+				break;
+			case 1: 
+				whatevers = java.util.Collections.singletonList(this.whatevers.get(0));
+				break;
+			default: 
+				whatevers = java.util.Collections.unmodifiableList(new java.util.ArrayList<String>(this.whatevers));
+			}
+			java.util.List<String> doohickeys;
+			switch (this.doohickeys == null ? 0 : this.doohickeys.size()) {
+			case 0: 
+				doohickeys = java.util.Collections.emptyList();
+				break;
+			case 1: 
+				doohickeys = java.util.Collections.singletonList(this.doohickeys.get(0));
+				break;
+			default: 
+				doohickeys = java.util.Collections.unmodifiableList(new java.util.ArrayList<String>(this.doohickeys));
+			}
+			return new BuilderSingularNullBehavior1(names, locations, whatevers, doohickeys);
+		}
+		@java.lang.Override
+		@java.lang.SuppressWarnings("all")
+		public java.lang.String toString() {
+			return "BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder(names=" + this.names + ", locations=" + this.locations + ", whatevers=" + this.whatevers + ", doohickeys=" + this.doohickeys + ")";
+		}
+	}
+	@java.lang.SuppressWarnings("all")
+	public static BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder builder() {
+		return new BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder();
+	}
+}
\ No newline at end of file
diff --git a/test/transform/resource/after-delombok/BuilderSingularRedirectToGuava.java b/test/transform/resource/after-delombok/BuilderSingularRedirectToGuava.java
index 4ce5cae5..9ee6823e 100644
--- a/test/transform/resource/after-delombok/BuilderSingularRedirectToGuava.java
+++ b/test/transform/resource/after-delombok/BuilderSingularRedirectToGuava.java
@@ -30,6 +30,7 @@ class BuilderSingularRedirectToGuava {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularRedirectToGuava.BuilderSingularRedirectToGuavaBuilder dangerMice(final java.lang.Iterable<? extends String> dangerMice) {
+			if (dangerMice == null) throw new java.lang.NullPointerException("dangerMice cannot be null");
 			if (this.dangerMice == null) this.dangerMice = com.google.common.collect.ImmutableSet.builder();
 			this.dangerMice.addAll(dangerMice);
 			return this;
@@ -47,6 +48,7 @@ class BuilderSingularRedirectToGuava {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularRedirectToGuava.BuilderSingularRedirectToGuavaBuilder things(final java.util.Map<? extends Integer, ? extends Number> things) {
+			if (things == null) throw new java.lang.NullPointerException("things cannot be null");
 			if (this.things == null) this.things = com.google.common.collect.ImmutableSortedMap.naturalOrder();
 			this.things.putAll(things);
 			return this;
@@ -64,6 +66,7 @@ class BuilderSingularRedirectToGuava {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularRedirectToGuava.BuilderSingularRedirectToGuavaBuilder doohickeys(final java.lang.Iterable<? extends Class<?>> doohickeys) {
+			if (doohickeys == null) throw new java.lang.NullPointerException("doohickeys cannot be null");
 			if (this.doohickeys == null) this.doohickeys = com.google.common.collect.ImmutableList.builder();
 			this.doohickeys.addAll(doohickeys);
 			return this;
diff --git a/test/transform/resource/after-delombok/BuilderSingularSets.java b/test/transform/resource/after-delombok/BuilderSingularSets.java
index c85bbb99..7b905c8c 100644
--- a/test/transform/resource/after-delombok/BuilderSingularSets.java
+++ b/test/transform/resource/after-delombok/BuilderSingularSets.java
@@ -34,6 +34,7 @@ class BuilderSingularSets<T> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularSets.BuilderSingularSetsBuilder<T> dangerMice(final java.util.Collection<? extends T> dangerMice) {
+			if (dangerMice == null) throw new java.lang.NullPointerException("dangerMice cannot be null");
 			if (this.dangerMice == null) this.dangerMice = new java.util.ArrayList<T>();
 			this.dangerMice.addAll(dangerMice);
 			return this;
@@ -51,6 +52,7 @@ class BuilderSingularSets<T> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularSets.BuilderSingularSetsBuilder<T> octopodes(final java.util.Collection<? extends Number> octopodes) {
+			if (octopodes == null) throw new java.lang.NullPointerException("octopodes cannot be null");
 			if (this.octopodes == null) this.octopodes = new java.util.ArrayList<Number>();
 			this.octopodes.addAll(octopodes);
 			return this;
@@ -68,6 +70,7 @@ class BuilderSingularSets<T> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularSets.BuilderSingularSetsBuilder<T> rawSet(final java.util.Collection<?> rawSet) {
+			if (rawSet == null) throw new java.lang.NullPointerException("rawSet cannot be null");
 			if (this.rawSet == null) this.rawSet = new java.util.ArrayList<java.lang.Object>();
 			this.rawSet.addAll(rawSet);
 			return this;
@@ -85,6 +88,7 @@ class BuilderSingularSets<T> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularSets.BuilderSingularSetsBuilder<T> stringSet(final java.util.Collection<? extends String> stringSet) {
+			if (stringSet == null) throw new java.lang.NullPointerException("stringSet cannot be null");
 			if (this.stringSet == null) this.stringSet = new java.util.ArrayList<String>();
 			this.stringSet.addAll(stringSet);
 			return this;
diff --git a/test/transform/resource/after-delombok/BuilderSingularSetsWithSetterPrefix.java b/test/transform/resource/after-delombok/BuilderSingularSetsWithSetterPrefix.java
index 6c9abf2f..4a025624 100644
--- a/test/transform/resource/after-delombok/BuilderSingularSetsWithSetterPrefix.java
+++ b/test/transform/resource/after-delombok/BuilderSingularSetsWithSetterPrefix.java
@@ -34,6 +34,7 @@ class BuilderSingularSetsWithSetterPrefix<T> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularSetsWithSetterPrefix.BuilderSingularSetsWithSetterPrefixBuilder<T> withDangerMice(final java.util.Collection<? extends T> dangerMice) {
+			if (dangerMice == null) throw new java.lang.NullPointerException("dangerMice cannot be null");
 			if (this.dangerMice == null) this.dangerMice = new java.util.ArrayList<T>();
 			this.dangerMice.addAll(dangerMice);
 			return this;
@@ -51,6 +52,7 @@ class BuilderSingularSetsWithSetterPrefix<T> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularSetsWithSetterPrefix.BuilderSingularSetsWithSetterPrefixBuilder<T> withOctopodes(final java.util.Collection<? extends Number> octopodes) {
+			if (octopodes == null) throw new java.lang.NullPointerException("octopodes cannot be null");
 			if (this.octopodes == null) this.octopodes = new java.util.ArrayList<Number>();
 			this.octopodes.addAll(octopodes);
 			return this;
@@ -68,6 +70,7 @@ class BuilderSingularSetsWithSetterPrefix<T> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularSetsWithSetterPrefix.BuilderSingularSetsWithSetterPrefixBuilder<T> withRawSet(final java.util.Collection<?> rawSet) {
+			if (rawSet == null) throw new java.lang.NullPointerException("rawSet cannot be null");
 			if (this.rawSet == null) this.rawSet = new java.util.ArrayList<java.lang.Object>();
 			this.rawSet.addAll(rawSet);
 			return this;
@@ -85,6 +88,7 @@ class BuilderSingularSetsWithSetterPrefix<T> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularSetsWithSetterPrefix.BuilderSingularSetsWithSetterPrefixBuilder<T> withStringSet(final java.util.Collection<? extends String> stringSet) {
+			if (stringSet == null) throw new java.lang.NullPointerException("stringSet cannot be null");
 			if (this.stringSet == null) this.stringSet = new java.util.ArrayList<String>();
 			this.stringSet.addAll(stringSet);
 			return this;
diff --git a/test/transform/resource/after-delombok/BuilderSingularToBuilderWithNull.java b/test/transform/resource/after-delombok/BuilderSingularToBuilderWithNull.java
index 2166491b..9a5ea7b3 100644
--- a/test/transform/resource/after-delombok/BuilderSingularToBuilderWithNull.java
+++ b/test/transform/resource/after-delombok/BuilderSingularToBuilderWithNull.java
@@ -22,6 +22,7 @@ class BuilderSingularToBuilderWithNull {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularToBuilderWithNull.BuilderSingularToBuilderWithNullBuilder elems(final java.util.Collection<? extends String> elems) {
+			if (elems == null) throw new java.lang.NullPointerException("elems cannot be null");
 			if (this.elems == null) this.elems = new java.util.ArrayList<String>();
 			this.elems.addAll(elems);
 			return this;
diff --git a/test/transform/resource/after-delombok/BuilderSingularToBuilderWithNullWithSetterPrefix.java b/test/transform/resource/after-delombok/BuilderSingularToBuilderWithNullWithSetterPrefix.java
index 79f11978..1860ba60 100644
--- a/test/transform/resource/after-delombok/BuilderSingularToBuilderWithNullWithSetterPrefix.java
+++ b/test/transform/resource/after-delombok/BuilderSingularToBuilderWithNullWithSetterPrefix.java
@@ -22,6 +22,7 @@ class BuilderSingularToBuilderWithNullWithSetterPrefix {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularToBuilderWithNullWithSetterPrefix.BuilderSingularToBuilderWithNullWithSetterPrefixBuilder withElems(final java.util.Collection<? extends String> elems) {
+			if (elems == null) throw new java.lang.NullPointerException("elems cannot be null");
 			if (this.elems == null) this.elems = new java.util.ArrayList<String>();
 			this.elems.addAll(elems);
 			return this;
diff --git a/test/transform/resource/after-delombok/BuilderSingularWildcardListsWithToBuilder.java b/test/transform/resource/after-delombok/BuilderSingularWildcardListsWithToBuilder.java
index ec05ea2d..29e53768 100644
--- a/test/transform/resource/after-delombok/BuilderSingularWildcardListsWithToBuilder.java
+++ b/test/transform/resource/after-delombok/BuilderSingularWildcardListsWithToBuilder.java
@@ -25,6 +25,7 @@ class BuilderSingularWildcardListsWithToBuilder {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularWildcardListsWithToBuilder.BuilderSingularWildcardListsWithToBuilderBuilder objects(final java.util.Collection<?> objects) {
+			if (objects == null) throw new java.lang.NullPointerException("objects cannot be null");
 			if (this.objects == null) this.objects = new java.util.ArrayList<java.lang.Object>();
 			this.objects.addAll(objects);
 			return this;
@@ -42,6 +43,7 @@ class BuilderSingularWildcardListsWithToBuilder {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularWildcardListsWithToBuilder.BuilderSingularWildcardListsWithToBuilderBuilder numbers(final java.util.Collection<? extends Number> numbers) {
+			if (numbers == null) throw new java.lang.NullPointerException("numbers cannot be null");
 			if (this.numbers == null) this.numbers = new java.util.ArrayList<Number>();
 			this.numbers.addAll(numbers);
 			return this;
diff --git a/test/transform/resource/after-delombok/BuilderSingularWithPrefixes.java b/test/transform/resource/after-delombok/BuilderSingularWithPrefixes.java
index 976866d3..3aa48f5d 100644
--- a/test/transform/resource/after-delombok/BuilderSingularWithPrefixes.java
+++ b/test/transform/resource/after-delombok/BuilderSingularWithPrefixes.java
@@ -19,6 +19,7 @@ class BuilderSingularWithPrefixes {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularWithPrefixes.BuilderSingularWithPrefixesBuilder elems(final java.util.Collection<? extends String> elems) {
+			if (elems == null) throw new java.lang.NullPointerException("elems cannot be null");
 			if (this.elems == null) this.elems = new java.util.ArrayList<String>();
 			this.elems.addAll(elems);
 			return this;
diff --git a/test/transform/resource/after-delombok/BuilderSingularWithPrefixesWithSetterPrefix.java b/test/transform/resource/after-delombok/BuilderSingularWithPrefixesWithSetterPrefix.java
index e2be79de..513c3fe4 100644
--- a/test/transform/resource/after-delombok/BuilderSingularWithPrefixesWithSetterPrefix.java
+++ b/test/transform/resource/after-delombok/BuilderSingularWithPrefixesWithSetterPrefix.java
@@ -19,6 +19,7 @@ class BuilderSingularWithPrefixesWithSetterPrefix {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderSingularWithPrefixesWithSetterPrefix.BuilderSingularWithPrefixesWithSetterPrefixBuilder withElems(final java.util.Collection<? extends String> elems) {
+			if (elems == null) throw new java.lang.NullPointerException("elems cannot be null");
 			if (this.elems == null) this.elems = new java.util.ArrayList<String>();
 			this.elems.addAll(elems);
 			return this;
diff --git a/test/transform/resource/after-delombok/BuilderWithDeprecated.java b/test/transform/resource/after-delombok/BuilderWithDeprecated.java
index 65f8e4e7..584c8042 100644
--- a/test/transform/resource/after-delombok/BuilderWithDeprecated.java
+++ b/test/transform/resource/after-delombok/BuilderWithDeprecated.java
@@ -56,6 +56,7 @@ public class BuilderWithDeprecated {
 		@java.lang.Deprecated
 		@java.lang.SuppressWarnings("all")
 		public BuilderWithDeprecated.BuilderWithDeprecatedBuilder strings(final java.util.Collection<? extends String> strings) {
+			if (strings == null) throw new java.lang.NullPointerException("strings cannot be null");
 			if (this.strings == null) this.strings = new java.util.ArrayList<String>();
 			this.strings.addAll(strings);
 			return this;
@@ -76,6 +77,7 @@ public class BuilderWithDeprecated {
 		@java.lang.Deprecated
 		@java.lang.SuppressWarnings("all")
 		public BuilderWithDeprecated.BuilderWithDeprecatedBuilder numbers(final java.lang.Iterable<? extends Integer> numbers) {
+			if (numbers == null) throw new java.lang.NullPointerException("numbers cannot be null");
 			if (this.numbers == null) this.numbers = com.google.common.collect.ImmutableList.builder();
 			this.numbers.addAll(numbers);
 			return this;
diff --git a/test/transform/resource/after-delombok/BuilderWithToBuilder.java b/test/transform/resource/after-delombok/BuilderWithToBuilder.java
index aa47c430..20043861 100644
--- a/test/transform/resource/after-delombok/BuilderWithToBuilder.java
+++ b/test/transform/resource/after-delombok/BuilderWithToBuilder.java
@@ -50,6 +50,7 @@ class BuilderWithToBuilder<T> {
 		}
 		@java.lang.SuppressWarnings("all")
 		public BuilderWithToBuilder.BuilderWithToBuilderBuilder<T> bars(final java.util.Collection<? extends T> bars) {
+			if (bars == null) throw new java.lang.NullPointerException("bars cannot be null");
 			if (this.bars == null) this.bars = new java.util.ArrayList<T>();
 			this.bars.addAll(bars);
 			return this;
diff --git a/test/transform/resource/after-delombok/CheckerFrameworkBuilder.java b/test/transform/resource/after-delombok/CheckerFrameworkBuilder.java
index 1b993d2a..fad0cf2b 100644
--- a/test/transform/resource/after-delombok/CheckerFrameworkBuilder.java
+++ b/test/transform/resource/after-delombok/CheckerFrameworkBuilder.java
@@ -62,6 +62,7 @@ class CheckerFrameworkBuilder {
 		@org.checkerframework.checker.builder.qual.ReturnsReceiver
 		@java.lang.SuppressWarnings("all")
 		public CheckerFrameworkBuilder.CheckerFrameworkBuilderBuilder names(final java.util.Collection<? extends String> names) {
+			if (names == null) throw new java.lang.NullPointerException("names cannot be null");
 			if (this.names == null) this.names = new java.util.ArrayList<String>();
 			this.names.addAll(names);
 			return this;
diff --git a/test/transform/resource/after-delombok/CheckerFrameworkSuperBuilder.java b/test/transform/resource/after-delombok/CheckerFrameworkSuperBuilder.java
index 31e8bdb5..f2cde1c6 100644
--- a/test/transform/resource/after-delombok/CheckerFrameworkSuperBuilder.java
+++ b/test/transform/resource/after-delombok/CheckerFrameworkSuperBuilder.java
@@ -58,6 +58,7 @@ class CheckerFrameworkSuperBuilder {
 			@org.checkerframework.checker.builder.qual.ReturnsReceiver
 			@java.lang.SuppressWarnings("all")
 			public B names(final java.util.Collection<? extends String> names) {
+				if (names == null) throw new java.lang.NullPointerException("names cannot be null");
 				if (this.names == null) this.names = new java.util.ArrayList<String>();
 				this.names.addAll(names);
 				return self();
diff --git a/test/transform/resource/after-delombok/SuperBuilderBasic.java b/test/transform/resource/after-delombok/SuperBuilderBasic.java
index ef8df1cc..1447e9af 100644
--- a/test/transform/resource/after-delombok/SuperBuilderBasic.java
+++ b/test/transform/resource/after-delombok/SuperBuilderBasic.java
@@ -26,6 +26,7 @@ public class SuperBuilderBasic {
 			}

 			@java.lang.SuppressWarnings("all")

 			public B items(final java.util.Collection<? extends String> items) {

+				if (items == null) throw new java.lang.NullPointerException("items cannot be null");

 				if (this.items == null) this.items = new java.util.ArrayList<String>();

 				this.items.addAll(items);

 				return self();

diff --git a/test/transform/resource/after-delombok/SuperBuilderBasicToBuilder.java b/test/transform/resource/after-delombok/SuperBuilderBasicToBuilder.java
index e9e8774a..1c0d378d 100644
--- a/test/transform/resource/after-delombok/SuperBuilderBasicToBuilder.java
+++ b/test/transform/resource/after-delombok/SuperBuilderBasicToBuilder.java
@@ -69,6 +69,7 @@ public class SuperBuilderBasicToBuilder {
 			}

 			@java.lang.SuppressWarnings("all")

 			public B items(final java.util.Collection<? extends String> items) {

+				if (items == null) throw new java.lang.NullPointerException("items cannot be null");

 				if (this.items == null) this.items = new java.util.ArrayList<String>();

 				this.items.addAll(items);

 				return self();

diff --git a/test/transform/resource/after-delombok/SuperBuilderSingularAnnotatedTypes.java b/test/transform/resource/after-delombok/SuperBuilderSingularAnnotatedTypes.java
index 12c61096..865af859 100644
--- a/test/transform/resource/after-delombok/SuperBuilderSingularAnnotatedTypes.java
+++ b/test/transform/resource/after-delombok/SuperBuilderSingularAnnotatedTypes.java
@@ -32,6 +32,7 @@ class SuperBuilderSingularAnnotatedTypes {
 		}
 		@java.lang.SuppressWarnings("all")
 		public B foos(final java.util.Collection<? extends @MyAnnotation @NonNull String> foos) {
+			if (foos == null) throw new java.lang.NullPointerException("foos cannot be null");
 			if (this.foos == null) this.foos = new java.util.ArrayList<@MyAnnotation @NonNull String>();
 			this.foos.addAll(foos);
 			return self();
@@ -59,6 +60,7 @@ class SuperBuilderSingularAnnotatedTypes {
 		}
 		@java.lang.SuppressWarnings("all")
 		public B bars(final java.util.Map<? extends @MyAnnotation @NonNull String, ? extends @MyAnnotation @NonNull Integer> bars) {
+			if (bars == null) throw new java.lang.NullPointerException("bars cannot be null");
 			if (this.bars$key == null) {
 				this.bars$key = new java.util.ArrayList<@MyAnnotation @NonNull String>();
 				this.bars$value = new java.util.ArrayList<@MyAnnotation @NonNull Integer>();
diff --git a/test/transform/resource/after-delombok/SuperBuilderWithCustomBuilderMethod.java b/test/transform/resource/after-delombok/SuperBuilderWithCustomBuilderMethod.java
index e042b238..4300a5ec 100644
--- a/test/transform/resource/after-delombok/SuperBuilderWithCustomBuilderMethod.java
+++ b/test/transform/resource/after-delombok/SuperBuilderWithCustomBuilderMethod.java
@@ -26,6 +26,7 @@ public class SuperBuilderWithCustomBuilderMethod {
 			}

 			@java.lang.SuppressWarnings("all")

 			public B items(final java.util.Collection<? extends String> items) {

+				if (items == null) throw new java.lang.NullPointerException("items cannot be null");

 				if (this.items == null) this.items = new java.util.ArrayList<String>();

 				this.items.addAll(items);

 				return self();

diff --git a/test/transform/resource/after-delombok/SuperBuilderWithGenerics.java b/test/transform/resource/after-delombok/SuperBuilderWithGenerics.java
index 2bac58f2..6b3d2ff0 100644
--- a/test/transform/resource/after-delombok/SuperBuilderWithGenerics.java
+++ b/test/transform/resource/after-delombok/SuperBuilderWithGenerics.java
@@ -26,6 +26,7 @@ public class SuperBuilderWithGenerics {
 			}

 			@java.lang.SuppressWarnings("all")

 			public B items(final java.util.Collection<? extends String> items) {

+				if (items == null) throw new java.lang.NullPointerException("items cannot be null");

 				if (this.items == null) this.items = new java.util.ArrayList<String>();

 				this.items.addAll(items);

 				return self();

diff --git a/test/transform/resource/after-delombok/SuperBuilderWithGenerics2.java b/test/transform/resource/after-delombok/SuperBuilderWithGenerics2.java
index 0f4a6c54..b03cff07 100644
--- a/test/transform/resource/after-delombok/SuperBuilderWithGenerics2.java
+++ b/test/transform/resource/after-delombok/SuperBuilderWithGenerics2.java
@@ -26,6 +26,7 @@ public class SuperBuilderWithGenerics2 {
 			}

 			@java.lang.SuppressWarnings("all")

 			public B items(final java.util.Collection<? extends String> items) {

+				if (items == null) throw new java.lang.NullPointerException("items cannot be null");

 				if (this.items == null) this.items = new java.util.ArrayList<String>();

 				this.items.addAll(items);

 				return self();

diff --git a/test/transform/resource/after-delombok/SuperBuilderWithGenericsAndToBuilder.java b/test/transform/resource/after-delombok/SuperBuilderWithGenericsAndToBuilder.java
index a6c44c7f..7403ff10 100644
--- a/test/transform/resource/after-delombok/SuperBuilderWithGenericsAndToBuilder.java
+++ b/test/transform/resource/after-delombok/SuperBuilderWithGenericsAndToBuilder.java
@@ -42,6 +42,7 @@ public class SuperBuilderWithGenericsAndToBuilder {
 			}

 			@java.lang.SuppressWarnings("all")

 			public B items(final java.util.Map<? extends Integer, ? extends String> items) {

+				if (items == null) throw new java.lang.NullPointerException("items cannot be null");

 				if (this.items$key == null) {

 					this.items$key = new java.util.ArrayList<Integer>();

 					this.items$value = new java.util.ArrayList<String>();

diff --git a/test/transform/resource/after-delombok/SuperBuilderWithPrefixes.java b/test/transform/resource/after-delombok/SuperBuilderWithPrefixes.java
index 15c8d9b9..324a1443 100644
--- a/test/transform/resource/after-delombok/SuperBuilderWithPrefixes.java
+++ b/test/transform/resource/after-delombok/SuperBuilderWithPrefixes.java
@@ -32,6 +32,7 @@ class SuperBuilderWithPrefixes {
 		}
 		@java.lang.SuppressWarnings("all")
 		public B items(final java.util.Collection<? extends String> items) {
+			if (items == null) throw new java.lang.NullPointerException("items cannot be null");
 			if (this.items == null) this.items = new java.util.ArrayList<String>();
 			this.items.addAll(items);
 			return self();
diff --git a/test/transform/resource/after-ecj/BuilderDefaultsWarnings.java b/test/transform/resource/after-ecj/BuilderDefaultsWarnings.java
index cc995aa2..e9ecad90 100644
--- a/test/transform/resource/after-ecj/BuilderDefaultsWarnings.java
+++ b/test/transform/resource/after-ecj/BuilderDefaultsWarnings.java
@@ -23,6 +23,8 @@ public @Builder class BuilderDefaultsWarnings {
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderDefaultsWarnings.BuilderDefaultsWarningsBuilder items(final java.util.Collection<? extends String> items) {
+      if ((items == null))
+          throw new java.lang.NullPointerException("items cannot be null");
       if ((this.items == null))
           this.items = new java.util.ArrayList<String>();
       this.items.addAll(items);
diff --git a/test/transform/resource/after-ecj/BuilderSingularAnnotatedTypes.java b/test/transform/resource/after-ecj/BuilderSingularAnnotatedTypes.java
index 18c01c2e..a371de1c 100644
--- a/test/transform/resource/after-ecj/BuilderSingularAnnotatedTypes.java
+++ b/test/transform/resource/after-ecj/BuilderSingularAnnotatedTypes.java
@@ -25,6 +25,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularAnnotatedTypes.BuilderSingularAnnotatedTypesBuilder foos(final java.util.Collection<? extends @MyAnnotation @NonNull String> foos) {
+      if ((foos == null))
+          throw new java.lang.NullPointerException("foos cannot be null");
       if ((this.foos == null))
           this.foos = new java.util.ArrayList<@MyAnnotation @NonNull String>();
       this.foos.addAll(foos);
@@ -54,6 +56,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularAnnotatedTypes.BuilderSingularAnnotatedTypesBuilder bars(final java.util.Map<? extends @MyAnnotation @NonNull String, ? extends @MyAnnotation @NonNull Integer> bars) {
+      if ((bars == null))
+          throw new java.lang.NullPointerException("bars cannot be null");
       if ((this.bars$key == null))
           {
             this.bars$key = new java.util.ArrayList<@MyAnnotation @NonNull String>();
diff --git a/test/transform/resource/after-ecj/BuilderSingularAnnotatedTypesWithSetterPrefix.java b/test/transform/resource/after-ecj/BuilderSingularAnnotatedTypesWithSetterPrefix.java
index 20197f83..cbb73c2f 100644
--- a/test/transform/resource/after-ecj/BuilderSingularAnnotatedTypesWithSetterPrefix.java
+++ b/test/transform/resource/after-ecj/BuilderSingularAnnotatedTypesWithSetterPrefix.java
@@ -25,6 +25,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularAnnotatedTypesWithSetterPrefix.BuilderSingularAnnotatedTypesWithSetterPrefixBuilder withFoos(final java.util.Collection<? extends @MyAnnotation @NonNull String> foos) {
+      if ((foos == null))
+          throw new java.lang.NullPointerException("foos cannot be null");
       if ((this.foos == null))
           this.foos = new java.util.ArrayList<@MyAnnotation @NonNull String>();
       this.foos.addAll(foos);
@@ -54,6 +56,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularAnnotatedTypesWithSetterPrefix.BuilderSingularAnnotatedTypesWithSetterPrefixBuilder withBars(final java.util.Map<? extends @MyAnnotation @NonNull String, ? extends @MyAnnotation @NonNull Integer> bars) {
+      if ((bars == null))
+          throw new java.lang.NullPointerException("bars cannot be null");
       if ((this.bars$key == null))
           {
             this.bars$key = new java.util.ArrayList<@MyAnnotation @NonNull String>();
diff --git a/test/transform/resource/after-ecj/BuilderSingularGuavaListsSets.java b/test/transform/resource/after-ecj/BuilderSingularGuavaListsSets.java
index 88a3096f..d0c68234 100644
--- a/test/transform/resource/after-ecj/BuilderSingularGuavaListsSets.java
+++ b/test/transform/resource/after-ecj/BuilderSingularGuavaListsSets.java
@@ -21,6 +21,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularGuavaListsSets.BuilderSingularGuavaListsSetsBuilder<T> cards(final java.lang.Iterable<? extends T> cards) {
+      if ((cards == null))
+          throw new java.lang.NullPointerException("cards cannot be null");
       if ((this.cards == null))
           this.cards = com.google.common.collect.ImmutableList.builder();
       this.cards.addAll(cards);
@@ -37,6 +39,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularGuavaListsSets.BuilderSingularGuavaListsSetsBuilder<T> frogs(final java.lang.Iterable<? extends Number> frogs) {
+      if ((frogs == null))
+          throw new java.lang.NullPointerException("frogs cannot be null");
       if ((this.frogs == null))
           this.frogs = com.google.common.collect.ImmutableList.builder();
       this.frogs.addAll(frogs);
@@ -53,6 +57,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularGuavaListsSets.BuilderSingularGuavaListsSetsBuilder<T> rawSet(final java.lang.Iterable<?> rawSet) {
+      if ((rawSet == null))
+          throw new java.lang.NullPointerException("rawSet cannot be null");
       if ((this.rawSet == null))
           this.rawSet = com.google.common.collect.ImmutableSet.builder();
       this.rawSet.addAll(rawSet);
@@ -69,6 +75,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularGuavaListsSets.BuilderSingularGuavaListsSetsBuilder<T> passes(final java.lang.Iterable<? extends String> passes) {
+      if ((passes == null))
+          throw new java.lang.NullPointerException("passes cannot be null");
       if ((this.passes == null))
           this.passes = com.google.common.collect.ImmutableSortedSet.naturalOrder();
       this.passes.addAll(passes);
@@ -85,6 +93,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularGuavaListsSets.BuilderSingularGuavaListsSetsBuilder<T> users(final com.google.common.collect.Table<? extends Number, ? extends Number, ? extends String> users) {
+      if ((users == null))
+          throw new java.lang.NullPointerException("users cannot be null");
       if ((this.users == null))
           this.users = com.google.common.collect.ImmutableTable.builder();
       this.users.putAll(users);
diff --git a/test/transform/resource/after-ecj/BuilderSingularGuavaMaps.java b/test/transform/resource/after-ecj/BuilderSingularGuavaMaps.java
index 618ee8db..08c72f98 100644
--- a/test/transform/resource/after-ecj/BuilderSingularGuavaMaps.java
+++ b/test/transform/resource/after-ecj/BuilderSingularGuavaMaps.java
@@ -17,6 +17,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularGuavaMaps.BuilderSingularGuavaMapsBuilder<K, V> battleaxes(final java.util.Map<? extends K, ? extends V> battleaxes) {
+      if ((battleaxes == null))
+          throw new java.lang.NullPointerException("battleaxes cannot be null");
       if ((this.battleaxes == null))
           this.battleaxes = com.google.common.collect.ImmutableMap.builder();
       this.battleaxes.putAll(battleaxes);
@@ -33,6 +35,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularGuavaMaps.BuilderSingularGuavaMapsBuilder<K, V> vertices(final java.util.Map<? extends Integer, ? extends V> vertices) {
+      if ((vertices == null))
+          throw new java.lang.NullPointerException("vertices cannot be null");
       if ((this.vertices == null))
           this.vertices = com.google.common.collect.ImmutableSortedMap.naturalOrder();
       this.vertices.putAll(vertices);
@@ -49,6 +53,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularGuavaMaps.BuilderSingularGuavaMapsBuilder<K, V> rawMap(final java.util.Map<?, ?> rawMap) {
+      if ((rawMap == null))
+          throw new java.lang.NullPointerException("rawMap cannot be null");
       if ((this.rawMap == null))
           this.rawMap = com.google.common.collect.ImmutableBiMap.builder();
       this.rawMap.putAll(rawMap);
diff --git a/test/transform/resource/after-ecj/BuilderSingularLists.java b/test/transform/resource/after-ecj/BuilderSingularLists.java
index 66247c3f..c201a32b 100644
--- a/test/transform/resource/after-ecj/BuilderSingularLists.java
+++ b/test/transform/resource/after-ecj/BuilderSingularLists.java
@@ -17,6 +17,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularLists.BuilderSingularListsBuilder<T> children(final java.util.Collection<? extends T> children) {
+      if ((children == null))
+          throw new java.lang.NullPointerException("children cannot be null");
       if ((this.children == null))
           this.children = new java.util.ArrayList<T>();
       this.children.addAll(children);
@@ -34,6 +36,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularLists.BuilderSingularListsBuilder<T> scarves(final java.util.Collection<? extends Number> scarves) {
+      if ((scarves == null))
+          throw new java.lang.NullPointerException("scarves cannot be null");
       if ((this.scarves == null))
           this.scarves = new java.util.ArrayList<Number>();
       this.scarves.addAll(scarves);
@@ -51,6 +55,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularLists.BuilderSingularListsBuilder<T> rawList(final java.util.Collection<?> rawList) {
+      if ((rawList == null))
+          throw new java.lang.NullPointerException("rawList cannot be null");
       if ((this.rawList == null))
           this.rawList = new java.util.ArrayList<java.lang.Object>();
       this.rawList.addAll(rawList);
diff --git a/test/transform/resource/after-ecj/BuilderSingularMaps.java b/test/transform/resource/after-ecj/BuilderSingularMaps.java
index 977ee527..d53e7022 100644
--- a/test/transform/resource/after-ecj/BuilderSingularMaps.java
+++ b/test/transform/resource/after-ecj/BuilderSingularMaps.java
@@ -25,6 +25,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularMaps.BuilderSingularMapsBuilder<K, V> women(final java.util.Map<? extends K, ? extends V> women) {
+      if ((women == null))
+          throw new java.lang.NullPointerException("women cannot be null");
       if ((this.women$key == null))
           {
             this.women$key = new java.util.ArrayList<K>();
@@ -56,6 +58,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularMaps.BuilderSingularMapsBuilder<K, V> men(final java.util.Map<? extends K, ? extends Number> men) {
+      if ((men == null))
+          throw new java.lang.NullPointerException("men cannot be null");
       if ((this.men$key == null))
           {
             this.men$key = new java.util.ArrayList<K>();
@@ -87,6 +91,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularMaps.BuilderSingularMapsBuilder<K, V> rawMap(final java.util.Map<?, ?> rawMap) {
+      if ((rawMap == null))
+          throw new java.lang.NullPointerException("rawMap cannot be null");
       if ((this.rawMap$key == null))
           {
             this.rawMap$key = new java.util.ArrayList<java.lang.Object>();
@@ -118,6 +124,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularMaps.BuilderSingularMapsBuilder<K, V> stringMap(final java.util.Map<? extends String, ? extends V> stringMap) {
+      if ((stringMap == null))
+          throw new java.lang.NullPointerException("stringMap cannot be null");
       if ((this.stringMap$key == null))
           {
             this.stringMap$key = new java.util.ArrayList<String>();
diff --git a/test/transform/resource/after-ecj/BuilderSingularMapsWithSetterPrefix.java b/test/transform/resource/after-ecj/BuilderSingularMapsWithSetterPrefix.java
index 0832fdc0..0bddd22c 100644
--- a/test/transform/resource/after-ecj/BuilderSingularMapsWithSetterPrefix.java
+++ b/test/transform/resource/after-ecj/BuilderSingularMapsWithSetterPrefix.java
@@ -25,16 +25,19 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularMapsWithSetterPrefix.BuilderSingularMapsWithSetterPrefixBuilder<K, V> withWomen(final java.util.Map<? extends K, ? extends V> women) {
-      if ((this.women$key == null))
+      if ((women != null))
           {
-            this.women$key = new java.util.ArrayList<K>();
-            this.women$value = new java.util.ArrayList<V>();
+            if ((this.women$key == null))
+                {
+                  this.women$key = new java.util.ArrayList<K>();
+                  this.women$value = new java.util.ArrayList<V>();
+                }
+            for (java.util.Map.Entry<? extends K, ? extends V> $lombokEntry : women.entrySet()) 
+              {
+                this.women$key.add($lombokEntry.getKey());
+                this.women$value.add($lombokEntry.getValue());
+              }
           }
-      for (java.util.Map.Entry<? extends K, ? extends V> $lombokEntry : women.entrySet()) 
-        {
-          this.women$key.add($lombokEntry.getKey());
-          this.women$value.add($lombokEntry.getValue());
-        }
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularMapsWithSetterPrefix.BuilderSingularMapsWithSetterPrefixBuilder<K, V> clearWomen() {
@@ -56,16 +59,19 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularMapsWithSetterPrefix.BuilderSingularMapsWithSetterPrefixBuilder<K, V> withMen(final java.util.Map<? extends K, ? extends Number> men) {
-      if ((this.men$key == null))
+      if ((men != null))
           {
-            this.men$key = new java.util.ArrayList<K>();
-            this.men$value = new java.util.ArrayList<Number>();
+            if ((this.men$key == null))
+                {
+                  this.men$key = new java.util.ArrayList<K>();
+                  this.men$value = new java.util.ArrayList<Number>();
+                }
+            for (java.util.Map.Entry<? extends K, ? extends Number> $lombokEntry : men.entrySet()) 
+              {
+                this.men$key.add($lombokEntry.getKey());
+                this.men$value.add($lombokEntry.getValue());
+              }
           }
-      for (java.util.Map.Entry<? extends K, ? extends Number> $lombokEntry : men.entrySet()) 
-        {
-          this.men$key.add($lombokEntry.getKey());
-          this.men$value.add($lombokEntry.getValue());
-        }
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularMapsWithSetterPrefix.BuilderSingularMapsWithSetterPrefixBuilder<K, V> clearMen() {
@@ -87,16 +93,19 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularMapsWithSetterPrefix.BuilderSingularMapsWithSetterPrefixBuilder<K, V> withRawMap(final java.util.Map<?, ?> rawMap) {
-      if ((this.rawMap$key == null))
+      if ((rawMap != null))
           {
-            this.rawMap$key = new java.util.ArrayList<java.lang.Object>();
-            this.rawMap$value = new java.util.ArrayList<java.lang.Object>();
+            if ((this.rawMap$key == null))
+                {
+                  this.rawMap$key = new java.util.ArrayList<java.lang.Object>();
+                  this.rawMap$value = new java.util.ArrayList<java.lang.Object>();
+                }
+            for (java.util.Map.Entry<?, ?> $lombokEntry : rawMap.entrySet()) 
+              {
+                this.rawMap$key.add($lombokEntry.getKey());
+                this.rawMap$value.add($lombokEntry.getValue());
+              }
           }
-      for (java.util.Map.Entry<?, ?> $lombokEntry : rawMap.entrySet()) 
-        {
-          this.rawMap$key.add($lombokEntry.getKey());
-          this.rawMap$value.add($lombokEntry.getValue());
-        }
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularMapsWithSetterPrefix.BuilderSingularMapsWithSetterPrefixBuilder<K, V> clearRawMap() {
@@ -118,16 +127,19 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularMapsWithSetterPrefix.BuilderSingularMapsWithSetterPrefixBuilder<K, V> withStringMap(final java.util.Map<? extends String, ? extends V> stringMap) {
-      if ((this.stringMap$key == null))
+      if ((stringMap != null))
           {
-            this.stringMap$key = new java.util.ArrayList<String>();
-            this.stringMap$value = new java.util.ArrayList<V>();
+            if ((this.stringMap$key == null))
+                {
+                  this.stringMap$key = new java.util.ArrayList<String>();
+                  this.stringMap$value = new java.util.ArrayList<V>();
+                }
+            for (java.util.Map.Entry<? extends String, ? extends V> $lombokEntry : stringMap.entrySet()) 
+              {
+                this.stringMap$key.add($lombokEntry.getKey());
+                this.stringMap$value.add($lombokEntry.getValue());
+              }
           }
-      for (java.util.Map.Entry<? extends String, ? extends V> $lombokEntry : stringMap.entrySet()) 
-        {
-          this.stringMap$key.add($lombokEntry.getKey());
-          this.stringMap$value.add($lombokEntry.getValue());
-        }
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularMapsWithSetterPrefix.BuilderSingularMapsWithSetterPrefixBuilder<K, V> clearStringMap() {
@@ -206,4 +218,4 @@ import lombok.Singular;
   public static @java.lang.SuppressWarnings("all") <K, V>BuilderSingularMapsWithSetterPrefix.BuilderSingularMapsWithSetterPrefixBuilder<K, V> builder() {
     return new BuilderSingularMapsWithSetterPrefix.BuilderSingularMapsWithSetterPrefixBuilder<K, V>();
   }
-}
+}
\ No newline at end of file
diff --git a/test/transform/resource/after-ecj/BuilderSingularNoAuto.java b/test/transform/resource/after-ecj/BuilderSingularNoAuto.java
index c1ac51eb..47b413b3 100644
--- a/test/transform/resource/after-ecj/BuilderSingularNoAuto.java
+++ b/test/transform/resource/after-ecj/BuilderSingularNoAuto.java
@@ -15,6 +15,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularNoAuto.BuilderSingularNoAutoBuilder things(final java.util.Collection<? extends String> things) {
+      if ((things == null))
+          throw new java.lang.NullPointerException("things cannot be null");
       if ((this.things == null))
           this.things = new java.util.ArrayList<String>();
       this.things.addAll(things);
@@ -32,6 +34,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularNoAuto.BuilderSingularNoAutoBuilder widgets(final java.util.Collection<? extends String> widgets) {
+      if ((widgets == null))
+          throw new java.lang.NullPointerException("widgets cannot be null");
       if ((this.widgets == null))
           this.widgets = new java.util.ArrayList<String>();
       this.widgets.addAll(widgets);
@@ -49,6 +53,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularNoAuto.BuilderSingularNoAutoBuilder items(final java.util.Collection<? extends String> items) {
+      if ((items == null))
+          throw new java.lang.NullPointerException("items cannot be null");
       if ((this.items == null))
           this.items = new java.util.ArrayList<String>();
       this.items.addAll(items);
diff --git a/test/transform/resource/after-ecj/BuilderSingularNoAutoWithSetterPrefix.java b/test/transform/resource/after-ecj/BuilderSingularNoAutoWithSetterPrefix.java
index e869e871..85cfda71 100644
--- a/test/transform/resource/after-ecj/BuilderSingularNoAutoWithSetterPrefix.java
+++ b/test/transform/resource/after-ecj/BuilderSingularNoAutoWithSetterPrefix.java
@@ -15,6 +15,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularNoAutoWithSetterPrefix.BuilderSingularNoAutoWithSetterPrefixBuilder withThings(final java.util.Collection<? extends String> things) {
+      if ((things == null))
+          throw new java.lang.NullPointerException("things cannot be null");
       if ((this.things == null))
           this.things = new java.util.ArrayList<String>();
       this.things.addAll(things);
@@ -32,6 +34,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularNoAutoWithSetterPrefix.BuilderSingularNoAutoWithSetterPrefixBuilder withWidgets(final java.util.Collection<? extends String> widgets) {
+      if ((widgets == null))
+          throw new java.lang.NullPointerException("widgets cannot be null");
       if ((this.widgets == null))
           this.widgets = new java.util.ArrayList<String>();
       this.widgets.addAll(widgets);
@@ -49,6 +53,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularNoAutoWithSetterPrefix.BuilderSingularNoAutoWithSetterPrefixBuilder withItems(final java.util.Collection<? extends String> items) {
+      if ((items == null))
+          throw new java.lang.NullPointerException("items cannot be null");
       if ((this.items == null))
           this.items = new java.util.ArrayList<String>();
       this.items.addAll(items);
diff --git a/test/transform/resource/after-ecj/BuilderSingularNullBehavior1.java b/test/transform/resource/after-ecj/BuilderSingularNullBehavior1.java
new file mode 100644
index 00000000..7ef52eb8
--- /dev/null
+++ b/test/transform/resource/after-ecj/BuilderSingularNullBehavior1.java
@@ -0,0 +1,154 @@
+import java.util.List;
+import java.util.Collection;
+import lombok.Singular;
+import lombok.Singular.NullCollectionBehavior;
+@lombok.Builder class BuilderSingularNullBehavior1 {
+  public static @java.lang.SuppressWarnings("all") class BuilderSingularNullBehavior1Builder {
+    private @java.lang.SuppressWarnings("all") java.util.ArrayList<String> names;
+    private @java.lang.SuppressWarnings("all") java.util.ArrayList<String> locations;
+    private @java.lang.SuppressWarnings("all") java.util.ArrayList<String> whatevers;
+    private @java.lang.SuppressWarnings("all") java.util.ArrayList<String> doohickeys;
+    @java.lang.SuppressWarnings("all") BuilderSingularNullBehavior1Builder() {
+      super();
+    }
+    public @java.lang.SuppressWarnings("all") BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder name(final String name) {
+      if ((this.names == null))
+          this.names = new java.util.ArrayList<String>();
+      this.names.add(name);
+      return this;
+    }
+    public @java.lang.SuppressWarnings("all") BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder names(final java.util.Collection<? extends String> names) {
+      if ((names == null))
+          throw new java.lang.NullPointerException("names cannot be null");
+      if ((this.names == null))
+          this.names = new java.util.ArrayList<String>();
+      this.names.addAll(names);
+      return this;
+    }
+    public @java.lang.SuppressWarnings("all") BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder clearNames() {
+      if ((this.names != null))
+          this.names.clear();
+      return this;
+    }
+    public @java.lang.SuppressWarnings("all") BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder location(final String location) {
+      if ((this.locations == null))
+          this.locations = new java.util.ArrayList<String>();
+      this.locations.add(location);
+      return this;
+    }
+    public @java.lang.SuppressWarnings("all") BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder locations(final java.util.Collection<? extends String> locations) {
+      java.util.Objects.requireNonNull(locations, "locations cannot be null");
+      if ((this.locations == null))
+          this.locations = new java.util.ArrayList<String>();
+      this.locations.addAll(locations);
+      return this;
+    }
+    public @java.lang.SuppressWarnings("all") BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder clearLocations() {
+      if ((this.locations != null))
+          this.locations.clear();
+      return this;
+    }
+    public @java.lang.SuppressWarnings("all") BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder whatever(final String whatever) {
+      if ((this.whatevers == null))
+          this.whatevers = new java.util.ArrayList<String>();
+      this.whatevers.add(whatever);
+      return this;
+    }
+    public @java.lang.SuppressWarnings("all") BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder whatevers(final java.util.Collection<? extends String> whatevers) {
+      com.google.common.base.Preconditions.checkNotNull(whatevers, "whatevers cannot be null");
+      if ((this.whatevers == null))
+          this.whatevers = new java.util.ArrayList<String>();
+      this.whatevers.addAll(whatevers);
+      return this;
+    }
+    public @java.lang.SuppressWarnings("all") BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder clearWhatevers() {
+      if ((this.whatevers != null))
+          this.whatevers.clear();
+      return this;
+    }
+    public @java.lang.SuppressWarnings("all") BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder doohickey(final String doohickey) {
+      if ((this.doohickeys == null))
+          this.doohickeys = new java.util.ArrayList<String>();
+      this.doohickeys.add(doohickey);
+      return this;
+    }
+    public @java.lang.SuppressWarnings("all") BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder doohickeys(final java.util.Collection<? extends String> doohickeys) {
+      if ((doohickeys != null))
+          {
+            if ((this.doohickeys == null))
+                this.doohickeys = new java.util.ArrayList<String>();
+            this.doohickeys.addAll(doohickeys);
+          }
+      return this;
+    }
+    public @java.lang.SuppressWarnings("all") BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder clearDoohickeys() {
+      if ((this.doohickeys != null))
+          this.doohickeys.clear();
+      return this;
+    }
+    public @java.lang.SuppressWarnings("all") BuilderSingularNullBehavior1 build() {
+      java.util.List<String> names;
+      switch (((this.names == null) ? 0 : this.names.size())) {
+      case 0 :
+          names = java.util.Collections.emptyList();
+          break;
+      case 1 :
+          names = java.util.Collections.singletonList(this.names.get(0));
+          break;
+      default :
+          names = java.util.Collections.unmodifiableList(new java.util.ArrayList<String>(this.names));
+      }
+      java.util.List<String> locations;
+      switch (((this.locations == null) ? 0 : this.locations.size())) {
+      case 0 :
+          locations = java.util.Collections.emptyList();
+          break;
+      case 1 :
+          locations = java.util.Collections.singletonList(this.locations.get(0));
+          break;
+      default :
+          locations = java.util.Collections.unmodifiableList(new java.util.ArrayList<String>(this.locations));
+      }
+      java.util.List<String> whatevers;
+      switch (((this.whatevers == null) ? 0 : this.whatevers.size())) {
+      case 0 :
+          whatevers = java.util.Collections.emptyList();
+          break;
+      case 1 :
+          whatevers = java.util.Collections.singletonList(this.whatevers.get(0));
+          break;
+      default :
+          whatevers = java.util.Collections.unmodifiableList(new java.util.ArrayList<String>(this.whatevers));
+      }
+      java.util.List<String> doohickeys;
+      switch (((this.doohickeys == null) ? 0 : this.doohickeys.size())) {
+      case 0 :
+          doohickeys = java.util.Collections.emptyList();
+          break;
+      case 1 :
+          doohickeys = java.util.Collections.singletonList(this.doohickeys.get(0));
+          break;
+      default :
+          doohickeys = java.util.Collections.unmodifiableList(new java.util.ArrayList<String>(this.doohickeys));
+      }
+      return new BuilderSingularNullBehavior1(names, locations, whatevers, doohickeys);
+    }
+    public @java.lang.Override @java.lang.SuppressWarnings("all") java.lang.String toString() {
+      return (((((((("BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder(names=" + this.names) + ", locations=") + this.locations) + ", whatevers=") + this.whatevers) + ", doohickeys=") + this.doohickeys) + ")");
+    }
+  }
+  private @Singular List<String> names;
+  private @Singular(nullBehavior = Singular.NullCollectionBehavior.JDK) List<String> locations;
+  private @Singular(nullBehavior = NullCollectionBehavior.GUAVA) List<String> whatevers;
+  private @Singular(nullBehavior = lombok.Singular.NullCollectionBehavior.IGNORE) List<String> doohickeys;
+  @java.lang.SuppressWarnings("all") BuilderSingularNullBehavior1(final List<String> names, final List<String> locations, final List<String> whatevers, final List<String> doohickeys) {
+    super();
+    this.names = names;
+    this.locations = locations;
+    this.whatevers = whatevers;
+    this.doohickeys = doohickeys;
+  }
+  public static @java.lang.SuppressWarnings("all") BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder builder() {
+    return new BuilderSingularNullBehavior1.BuilderSingularNullBehavior1Builder();
+  }
+}
\ No newline at end of file
diff --git a/test/transform/resource/after-ecj/BuilderSingularRedirectToGuava.java b/test/transform/resource/after-ecj/BuilderSingularRedirectToGuava.java
index 9e7028d6..867bf7fa 100644
--- a/test/transform/resource/after-ecj/BuilderSingularRedirectToGuava.java
+++ b/test/transform/resource/after-ecj/BuilderSingularRedirectToGuava.java
@@ -17,6 +17,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularRedirectToGuava.BuilderSingularRedirectToGuavaBuilder dangerMice(final java.lang.Iterable<? extends String> dangerMice) {
+      if ((dangerMice == null))
+          throw new java.lang.NullPointerException("dangerMice cannot be null");
       if ((this.dangerMice == null))
           this.dangerMice = com.google.common.collect.ImmutableSet.builder();
       this.dangerMice.addAll(dangerMice);
@@ -33,6 +35,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularRedirectToGuava.BuilderSingularRedirectToGuavaBuilder things(final java.util.Map<? extends Integer, ? extends Number> things) {
+      if ((things == null))
+          throw new java.lang.NullPointerException("things cannot be null");
       if ((this.things == null))
           this.things = com.google.common.collect.ImmutableSortedMap.naturalOrder();
       this.things.putAll(things);
@@ -49,6 +53,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularRedirectToGuava.BuilderSingularRedirectToGuavaBuilder doohickeys(final java.lang.Iterable<? extends Class<?>> doohickeys) {
+      if ((doohickeys == null))
+          throw new java.lang.NullPointerException("doohickeys cannot be null");
       if ((this.doohickeys == null))
           this.doohickeys = com.google.common.collect.ImmutableList.builder();
       this.doohickeys.addAll(doohickeys);
diff --git a/test/transform/resource/after-ecj/BuilderSingularSets.java b/test/transform/resource/after-ecj/BuilderSingularSets.java
index b6ef04cb..6cfa5203 100644
--- a/test/transform/resource/after-ecj/BuilderSingularSets.java
+++ b/test/transform/resource/after-ecj/BuilderSingularSets.java
@@ -17,6 +17,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularSets.BuilderSingularSetsBuilder<T> dangerMice(final java.util.Collection<? extends T> dangerMice) {
+      if ((dangerMice == null))
+          throw new java.lang.NullPointerException("dangerMice cannot be null");
       if ((this.dangerMice == null))
           this.dangerMice = new java.util.ArrayList<T>();
       this.dangerMice.addAll(dangerMice);
@@ -34,6 +36,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularSets.BuilderSingularSetsBuilder<T> octopodes(final java.util.Collection<? extends Number> octopodes) {
+      if ((octopodes == null))
+          throw new java.lang.NullPointerException("octopodes cannot be null");
       if ((this.octopodes == null))
           this.octopodes = new java.util.ArrayList<Number>();
       this.octopodes.addAll(octopodes);
@@ -51,6 +55,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularSets.BuilderSingularSetsBuilder<T> rawSet(final java.util.Collection<?> rawSet) {
+      if ((rawSet == null))
+          throw new java.lang.NullPointerException("rawSet cannot be null");
       if ((this.rawSet == null))
           this.rawSet = new java.util.ArrayList<java.lang.Object>();
       this.rawSet.addAll(rawSet);
@@ -68,6 +74,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularSets.BuilderSingularSetsBuilder<T> stringSet(final java.util.Collection<? extends String> stringSet) {
+      if ((stringSet == null))
+          throw new java.lang.NullPointerException("stringSet cannot be null");
       if ((this.stringSet == null))
           this.stringSet = new java.util.ArrayList<String>();
       this.stringSet.addAll(stringSet);
diff --git a/test/transform/resource/after-ecj/BuilderSingularSetsWithSetterPrefix.java b/test/transform/resource/after-ecj/BuilderSingularSetsWithSetterPrefix.java
index b857b586..cdc0390c 100644
--- a/test/transform/resource/after-ecj/BuilderSingularSetsWithSetterPrefix.java
+++ b/test/transform/resource/after-ecj/BuilderSingularSetsWithSetterPrefix.java
@@ -17,6 +17,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularSetsWithSetterPrefix.BuilderSingularSetsWithSetterPrefixBuilder<T> withDangerMice(final java.util.Collection<? extends T> dangerMice) {
+      if ((dangerMice == null))
+          throw new java.lang.NullPointerException("dangerMice cannot be null");
       if ((this.dangerMice == null))
           this.dangerMice = new java.util.ArrayList<T>();
       this.dangerMice.addAll(dangerMice);
@@ -34,6 +36,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularSetsWithSetterPrefix.BuilderSingularSetsWithSetterPrefixBuilder<T> withOctopodes(final java.util.Collection<? extends Number> octopodes) {
+      if ((octopodes == null))
+          throw new java.lang.NullPointerException("octopodes cannot be null");
       if ((this.octopodes == null))
           this.octopodes = new java.util.ArrayList<Number>();
       this.octopodes.addAll(octopodes);
@@ -51,6 +55,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularSetsWithSetterPrefix.BuilderSingularSetsWithSetterPrefixBuilder<T> withRawSet(final java.util.Collection<?> rawSet) {
+      if ((rawSet == null))
+          throw new java.lang.NullPointerException("rawSet cannot be null");
       if ((this.rawSet == null))
           this.rawSet = new java.util.ArrayList<java.lang.Object>();
       this.rawSet.addAll(rawSet);
@@ -68,6 +74,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularSetsWithSetterPrefix.BuilderSingularSetsWithSetterPrefixBuilder<T> withStringSet(final java.util.Collection<? extends String> stringSet) {
+      if ((stringSet == null))
+          throw new java.lang.NullPointerException("stringSet cannot be null");
       if ((this.stringSet == null))
           this.stringSet = new java.util.ArrayList<String>();
       this.stringSet.addAll(stringSet);
diff --git a/test/transform/resource/after-ecj/BuilderSingularToBuilderWithNull.java b/test/transform/resource/after-ecj/BuilderSingularToBuilderWithNull.java
index 99a277e3..c01b5b8f 100644
--- a/test/transform/resource/after-ecj/BuilderSingularToBuilderWithNull.java
+++ b/test/transform/resource/after-ecj/BuilderSingularToBuilderWithNull.java
@@ -12,6 +12,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularToBuilderWithNull.BuilderSingularToBuilderWithNullBuilder elems(final java.util.Collection<? extends String> elems) {
+      if ((elems == null))
+          throw new java.lang.NullPointerException("elems cannot be null");
       if ((this.elems == null))
           this.elems = new java.util.ArrayList<String>();
       this.elems.addAll(elems);
diff --git a/test/transform/resource/after-ecj/BuilderSingularToBuilderWithNullWithSetterPrefix.java b/test/transform/resource/after-ecj/BuilderSingularToBuilderWithNullWithSetterPrefix.java
index a0223598..092f0b55 100644
--- a/test/transform/resource/after-ecj/BuilderSingularToBuilderWithNullWithSetterPrefix.java
+++ b/test/transform/resource/after-ecj/BuilderSingularToBuilderWithNullWithSetterPrefix.java
@@ -12,6 +12,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularToBuilderWithNullWithSetterPrefix.BuilderSingularToBuilderWithNullWithSetterPrefixBuilder withElems(final java.util.Collection<? extends String> elems) {
+      if ((elems == null))
+          throw new java.lang.NullPointerException("elems cannot be null");
       if ((this.elems == null))
           this.elems = new java.util.ArrayList<String>();
       this.elems.addAll(elems);
diff --git a/test/transform/resource/after-ecj/BuilderSingularWildcardListsWithToBuilder.java b/test/transform/resource/after-ecj/BuilderSingularWildcardListsWithToBuilder.java
index e9c61eb6..8a00644d 100644
--- a/test/transform/resource/after-ecj/BuilderSingularWildcardListsWithToBuilder.java
+++ b/test/transform/resource/after-ecj/BuilderSingularWildcardListsWithToBuilder.java
@@ -15,6 +15,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularWildcardListsWithToBuilder.BuilderSingularWildcardListsWithToBuilderBuilder objects(final java.util.Collection<?> objects) {
+      if ((objects == null))
+          throw new java.lang.NullPointerException("objects cannot be null");
       if ((this.objects == null))
           this.objects = new java.util.ArrayList<java.lang.Object>();
       this.objects.addAll(objects);
@@ -32,6 +34,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularWildcardListsWithToBuilder.BuilderSingularWildcardListsWithToBuilderBuilder numbers(final java.util.Collection<? extends Number> numbers) {
+      if ((numbers == null))
+          throw new java.lang.NullPointerException("numbers cannot be null");
       if ((this.numbers == null))
           this.numbers = new java.util.ArrayList<Number>();
       this.numbers.addAll(numbers);
diff --git a/test/transform/resource/after-ecj/BuilderSingularWithPrefixes.java b/test/transform/resource/after-ecj/BuilderSingularWithPrefixes.java
index 5f8a8ee0..b4fa5cbe 100644
--- a/test/transform/resource/after-ecj/BuilderSingularWithPrefixes.java
+++ b/test/transform/resource/after-ecj/BuilderSingularWithPrefixes.java
@@ -12,6 +12,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularWithPrefixes.BuilderSingularWithPrefixesBuilder elems(final java.util.Collection<? extends String> elems) {
+      if ((elems == null))
+          throw new java.lang.NullPointerException("elems cannot be null");
       if ((this.elems == null))
           this.elems = new java.util.ArrayList<String>();
       this.elems.addAll(elems);
diff --git a/test/transform/resource/after-ecj/BuilderSingularWithPrefixesWithSetterPrefix.java b/test/transform/resource/after-ecj/BuilderSingularWithPrefixesWithSetterPrefix.java
index 377a9c27..f10482d5 100644
--- a/test/transform/resource/after-ecj/BuilderSingularWithPrefixesWithSetterPrefix.java
+++ b/test/transform/resource/after-ecj/BuilderSingularWithPrefixesWithSetterPrefix.java
@@ -12,6 +12,8 @@ import lombok.Singular;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularWithPrefixesWithSetterPrefix.BuilderSingularWithPrefixesWithSetterPrefixBuilder withElems(final java.util.Collection<? extends String> elems) {
+      if ((elems == null))
+          throw new java.lang.NullPointerException("elems cannot be null");
       if ((this.elems == null))
           this.elems = new java.util.ArrayList<String>();
       this.elems.addAll(elems);
diff --git a/test/transform/resource/after-ecj/BuilderWithDeprecated.java b/test/transform/resource/after-ecj/BuilderWithDeprecated.java
index 24d35df1..9dcddc49 100644
--- a/test/transform/resource/after-ecj/BuilderWithDeprecated.java
+++ b/test/transform/resource/after-ecj/BuilderWithDeprecated.java
@@ -25,6 +25,8 @@ public @Builder class BuilderWithDeprecated {
       return this;
     }
     public @java.lang.Deprecated @java.lang.SuppressWarnings("all") BuilderWithDeprecated.BuilderWithDeprecatedBuilder strings(final java.util.Collection<? extends String> strings) {
+      if ((strings == null))
+          throw new java.lang.NullPointerException("strings cannot be null");
       if ((this.strings == null))
           this.strings = new java.util.ArrayList<String>();
       this.strings.addAll(strings);
@@ -42,6 +44,8 @@ public @Builder class BuilderWithDeprecated {
       return this;
     }
     public @java.lang.Deprecated @java.lang.SuppressWarnings("all") BuilderWithDeprecated.BuilderWithDeprecatedBuilder numbers(final java.lang.Iterable<? extends Integer> numbers) {
+      if ((numbers == null))
+          throw new java.lang.NullPointerException("numbers cannot be null");
       if ((this.numbers == null))
           this.numbers = com.google.common.collect.ImmutableList.builder();
       this.numbers.addAll(numbers);
diff --git a/test/transform/resource/after-ecj/BuilderWithToBuilder.java b/test/transform/resource/after-ecj/BuilderWithToBuilder.java
index 6d935736..ec72bdb8 100644
--- a/test/transform/resource/after-ecj/BuilderWithToBuilder.java
+++ b/test/transform/resource/after-ecj/BuilderWithToBuilder.java
@@ -28,6 +28,8 @@ import lombok.Builder;
       return this;
     }
     public @java.lang.SuppressWarnings("all") BuilderWithToBuilder.BuilderWithToBuilderBuilder<T> bars(final java.util.Collection<? extends T> bars) {
+      if ((bars == null))
+          throw new java.lang.NullPointerException("bars cannot be null");
       if ((this.bars == null))
           this.bars = new java.util.ArrayList<T>();
       this.bars.addAll(bars);
diff --git a/test/transform/resource/after-ecj/CheckerFrameworkBuilder.java b/test/transform/resource/after-ecj/CheckerFrameworkBuilder.java
index d2163ef5..d9201e39 100644
--- a/test/transform/resource/after-ecj/CheckerFrameworkBuilder.java
+++ b/test/transform/resource/after-ecj/CheckerFrameworkBuilder.java
@@ -31,6 +31,8 @@ import lombok.Singular;
       return this;
     }
     public @org.checkerframework.checker.builder.qual.ReturnsReceiver @java.lang.SuppressWarnings("all") CheckerFrameworkBuilder.CheckerFrameworkBuilderBuilder names(final java.util.Collection<? extends String> names) {
+      if ((names == null))
+          throw new java.lang.NullPointerException("names cannot be null");
       if ((this.names == null))
           this.names = new java.util.ArrayList<String>();
       this.names.addAll(names);
diff --git a/test/transform/resource/after-ecj/CheckerFrameworkSuperBuilder.java b/test/transform/resource/after-ecj/CheckerFrameworkSuperBuilder.java
index 1849419e..94ec0a0c 100644
--- a/test/transform/resource/after-ecj/CheckerFrameworkSuperBuilder.java
+++ b/test/transform/resource/after-ecj/CheckerFrameworkSuperBuilder.java
@@ -32,6 +32,8 @@ class CheckerFrameworkSuperBuilder {
         return self();
       }
       public @org.checkerframework.checker.builder.qual.ReturnsReceiver @java.lang.SuppressWarnings("all") B names(final java.util.Collection<? extends String> names) {
+        if ((names == null))
+            throw new java.lang.NullPointerException("names cannot be null");
         if ((this.names == null))
             this.names = new java.util.ArrayList<String>();
         this.names.addAll(names);
diff --git a/test/transform/resource/after-ecj/I2335_BuilderMultipleObtainVia.java b/test/transform/resource/after-ecj/I2335_BuilderMultipleObtainVia.java
index 7d8b8953..9c5eb6ae 100644
--- a/test/transform/resource/after-ecj/I2335_BuilderMultipleObtainVia.java
+++ b/test/transform/resource/after-ecj/I2335_BuilderMultipleObtainVia.java
@@ -44,8 +44,8 @@ public @Builder class I2335_BuilderMultipleObtainVia {
     return new I2335_BuilderMultipleObtainVia.I2335_BuilderMultipleObtainViaBuilder();
   }
   public @java.lang.SuppressWarnings("all") I2335_BuilderMultipleObtainVia.I2335_BuilderMultipleObtainViaBuilder toBuilder() {
-    String theString = this.getTheString();
-    Long theLong = this.getTheLong();
+    final String theString = this.getTheString();
+    final Long theLong = this.getTheLong();
     return new I2335_BuilderMultipleObtainVia.I2335_BuilderMultipleObtainViaBuilder().theString(theString).theLong(theLong);
   }
 }
diff --git a/test/transform/resource/after-ecj/SuperBuilderBasic.java b/test/transform/resource/after-ecj/SuperBuilderBasic.java
index dad0ad8f..9e686f0f 100644
--- a/test/transform/resource/after-ecj/SuperBuilderBasic.java
+++ b/test/transform/resource/after-ecj/SuperBuilderBasic.java
@@ -20,6 +20,8 @@ public class SuperBuilderBasic {
         return self();

       }

       public @java.lang.SuppressWarnings("all") B items(final java.util.Collection<? extends String> items) {

+        if ((items == null))

+            throw new java.lang.NullPointerException("items cannot be null");

         if ((this.items == null))

             this.items = new java.util.ArrayList<String>();

         this.items.addAll(items);

diff --git a/test/transform/resource/after-ecj/SuperBuilderBasicToBuilder.java b/test/transform/resource/after-ecj/SuperBuilderBasicToBuilder.java
index a9f111d0..e027c9d2 100644
--- a/test/transform/resource/after-ecj/SuperBuilderBasicToBuilder.java
+++ b/test/transform/resource/after-ecj/SuperBuilderBasicToBuilder.java
@@ -46,6 +46,8 @@ public class SuperBuilderBasicToBuilder {
         return self();

       }

       public @java.lang.SuppressWarnings("all") B items(final java.util.Collection<? extends String> items) {

+        if ((items == null))

+            throw new java.lang.NullPointerException("items cannot be null");

         if ((this.items == null))

             this.items = new java.util.ArrayList<String>();

         this.items.addAll(items);

diff --git a/test/transform/resource/after-ecj/SuperBuilderSingularAnnotatedTypes.java b/test/transform/resource/after-ecj/SuperBuilderSingularAnnotatedTypes.java
index 809ca50c..834d2180 100644
--- a/test/transform/resource/after-ecj/SuperBuilderSingularAnnotatedTypes.java
+++ b/test/transform/resource/after-ecj/SuperBuilderSingularAnnotatedTypes.java
@@ -27,6 +27,8 @@ import lombok.Singular;
       return self();
     }
     public @java.lang.SuppressWarnings("all") B foos(final java.util.Collection<? extends @MyAnnotation @NonNull String> foos) {
+      if ((foos == null))
+          throw new java.lang.NullPointerException("foos cannot be null");
       if ((this.foos == null))
           this.foos = new java.util.ArrayList<@MyAnnotation @NonNull String>();
       this.foos.addAll(foos);
@@ -56,6 +58,8 @@ import lombok.Singular;
       return self();
     }
     public @java.lang.SuppressWarnings("all") B bars(final java.util.Map<? extends @MyAnnotation @NonNull String, ? extends @MyAnnotation @NonNull Integer> bars) {
+      if ((bars == null))
+          throw new java.lang.NullPointerException("bars cannot be null");
       if ((this.bars$key == null))
           {
             this.bars$key = new java.util.ArrayList<@MyAnnotation @NonNull String>();
diff --git a/test/transform/resource/after-ecj/SuperBuilderWithCustomBuilderMethod.java b/test/transform/resource/after-ecj/SuperBuilderWithCustomBuilderMethod.java
index 751e281b..6605ae1d 100644
--- a/test/transform/resource/after-ecj/SuperBuilderWithCustomBuilderMethod.java
+++ b/test/transform/resource/after-ecj/SuperBuilderWithCustomBuilderMethod.java
@@ -20,6 +20,8 @@ public class SuperBuilderWithCustomBuilderMethod {
         return self();

       }

       public @java.lang.SuppressWarnings("all") B items(final java.util.Collection<? extends String> items) {

+        if ((items == null))

+            throw new java.lang.NullPointerException("items cannot be null");

         if ((this.items == null))

             this.items = new java.util.ArrayList<String>();

         this.items.addAll(items);

diff --git a/test/transform/resource/after-ecj/SuperBuilderWithGenerics.java b/test/transform/resource/after-ecj/SuperBuilderWithGenerics.java
index bbf07d75..89ab8821 100644
--- a/test/transform/resource/after-ecj/SuperBuilderWithGenerics.java
+++ b/test/transform/resource/after-ecj/SuperBuilderWithGenerics.java
@@ -20,6 +20,8 @@ public class SuperBuilderWithGenerics {
         return self();

       }

       public @java.lang.SuppressWarnings("all") B items(final java.util.Collection<? extends String> items) {

+        if ((items == null))

+            throw new java.lang.NullPointerException("items cannot be null");

         if ((this.items == null))

             this.items = new java.util.ArrayList<String>();

         this.items.addAll(items);

diff --git a/test/transform/resource/after-ecj/SuperBuilderWithGenerics2.java b/test/transform/resource/after-ecj/SuperBuilderWithGenerics2.java
index b3ca18ec..2037f7b0 100644
--- a/test/transform/resource/after-ecj/SuperBuilderWithGenerics2.java
+++ b/test/transform/resource/after-ecj/SuperBuilderWithGenerics2.java
@@ -20,6 +20,8 @@ public class SuperBuilderWithGenerics2 {
         return self();

       }

       public @java.lang.SuppressWarnings("all") B items(final java.util.Collection<? extends String> items) {

+        if ((items == null))

+            throw new java.lang.NullPointerException("items cannot be null");

         if ((this.items == null))

             this.items = new java.util.ArrayList<String>();

         this.items.addAll(items);

diff --git a/test/transform/resource/after-ecj/SuperBuilderWithGenericsAndToBuilder.java b/test/transform/resource/after-ecj/SuperBuilderWithGenericsAndToBuilder.java
index 457104ef..8b26e439 100644
--- a/test/transform/resource/after-ecj/SuperBuilderWithGenericsAndToBuilder.java
+++ b/test/transform/resource/after-ecj/SuperBuilderWithGenericsAndToBuilder.java
@@ -33,6 +33,8 @@ public class SuperBuilderWithGenericsAndToBuilder {
         return self();

       }

       public @java.lang.SuppressWarnings("all") B items(final java.util.Map<? extends Integer, ? extends String> items) {

+        if ((items == null))

+            throw new java.lang.NullPointerException("items cannot be null");

         if ((this.items$key == null))

             {

               this.items$key = new java.util.ArrayList<Integer>();

diff --git a/test/transform/resource/after-ecj/SuperBuilderWithPrefixes.java b/test/transform/resource/after-ecj/SuperBuilderWithPrefixes.java
index 51abbca4..e3b5baeb 100644
--- a/test/transform/resource/after-ecj/SuperBuilderWithPrefixes.java
+++ b/test/transform/resource/after-ecj/SuperBuilderWithPrefixes.java
@@ -23,6 +23,8 @@
       return self();
     }
     public @java.lang.SuppressWarnings("all") B items(final java.util.Collection<? extends String> items) {
+      if ((items == null))
+          throw new java.lang.NullPointerException("items cannot be null");
       if ((this.items == null))
           this.items = new java.util.ArrayList<String>();
       this.items.addAll(items);
diff --git a/test/transform/resource/before/BuilderSingularMapsWithSetterPrefix.java b/test/transform/resource/before/BuilderSingularMapsWithSetterPrefix.java
index 728ad59a..89beb401 100644
--- a/test/transform/resource/before/BuilderSingularMapsWithSetterPrefix.java
+++ b/test/transform/resource/before/BuilderSingularMapsWithSetterPrefix.java
@@ -1,6 +1,7 @@
 //FORMAT: javaLangAsFQN = skip
 //FORMAT: generated = skip
 //FORMAT: finalParams = skip
+//CONF: lombok.singular.nullCollections = ignore
 import java.util.Map;
 import java.util.SortedMap;
 
diff --git a/test/transform/resource/before/BuilderSingularNullBehavior1.java b/test/transform/resource/before/BuilderSingularNullBehavior1.java
new file mode 100644
index 00000000..019b6473
--- /dev/null
+++ b/test/transform/resource/before/BuilderSingularNullBehavior1.java
@@ -0,0 +1,13 @@
+import java.util.List;
+import java.util.Collection;
+
+import lombok.Singular;
+import lombok.Singular.NullCollectionBehavior;
+
+@lombok.Builder
+class BuilderSingularNullBehavior1 {
+	@Singular private List<String> names;
+	@Singular(nullBehavior = Singular.NullCollectionBehavior.JDK) private List<String> locations;
+	@Singular(nullBehavior = NullCollectionBehavior.GUAVA) private List<String> whatevers;
+	@Singular(nullBehavior = lombok.Singular.NullCollectionBehavior.IGNORE) private List<String> doohickeys;
+}