From 91a40b83125808d3684ce07c5cb4a2927d0b979c Mon Sep 17 00:00:00 2001
From: Reinier Zwitserloot <r.zwitserloot@projectlombok.org>
Date: Sat, 18 Jan 2020 03:10:07 +0100
Subject: [singular][issue #2221] the plural builder method now nullchecks its
 argument with configurable results.

---
 src/core/lombok/ConfigurationKeys.java             |  29 +++-
 src/core/lombok/Singular.java                      |  64 +++++++++
 .../core/configuration/NullCheckExceptionType.java |   4 +-
 src/core/lombok/core/handlers/HandlerUtil.java     |   7 +-
 .../eclipse/handlers/EclipseSingularsRecipes.java  |  59 +++++++-
 .../lombok/eclipse/handlers/HandleBuilder.java     |  18 ++-
 .../eclipse/handlers/HandleSuperBuilder.java       |   7 +-
 .../singulars/EclipseGuavaSingularizer.java        |   5 +-
 .../EclipseJavaUtilListSetSingularizer.java        |   4 +-
 .../singulars/EclipseJavaUtilMapSingularizer.java  |   5 +-
 src/core/lombok/javac/handlers/HandleBuilder.java  |  19 ++-
 .../lombok/javac/handlers/HandleSuperBuilder.java  |   7 +-
 .../javac/handlers/JavacSingularsRecipes.java      |  68 ++++++---
 test/core/src/lombok/DirectoryRunner.java          |   2 +-
 .../after-delombok/BuilderDefaultsWarnings.java    |   1 +
 .../BuilderSingularAnnotatedTypes.java             |   2 +
 ...lderSingularAnnotatedTypesWithSetterPrefix.java |   2 +
 .../BuilderSingularGuavaListsSets.java             |   5 +
 .../after-delombok/BuilderSingularGuavaMaps.java   |   3 +
 .../after-delombok/BuilderSingularLists.java       |   3 +
 .../after-delombok/BuilderSingularMaps.java        |   4 +
 .../BuilderSingularMapsWithSetterPrefix.java       |  64 +++++----
 .../after-delombok/BuilderSingularNoAuto.java      |   3 +
 .../BuilderSingularNoAutoWithSetterPrefix.java     |   3 +
 .../BuilderSingularNullBehavior1.java              | 160 +++++++++++++++++++++
 .../BuilderSingularRedirectToGuava.java            |   3 +
 .../after-delombok/BuilderSingularSets.java        |   4 +
 .../BuilderSingularSetsWithSetterPrefix.java       |   4 +
 .../BuilderSingularToBuilderWithNull.java          |   1 +
 ...rSingularToBuilderWithNullWithSetterPrefix.java |   1 +
 .../BuilderSingularWildcardListsWithToBuilder.java |   2 +
 .../BuilderSingularWithPrefixes.java               |   1 +
 ...uilderSingularWithPrefixesWithSetterPrefix.java |   1 +
 .../after-delombok/BuilderWithDeprecated.java      |   2 +
 .../after-delombok/BuilderWithToBuilder.java       |   1 +
 .../after-delombok/CheckerFrameworkBuilder.java    |   1 +
 .../CheckerFrameworkSuperBuilder.java              |   1 +
 .../resource/after-delombok/SuperBuilderBasic.java |   1 +
 .../after-delombok/SuperBuilderBasicToBuilder.java |   1 +
 .../SuperBuilderSingularAnnotatedTypes.java        |   2 +
 .../SuperBuilderWithCustomBuilderMethod.java       |   1 +
 .../after-delombok/SuperBuilderWithGenerics.java   |   1 +
 .../after-delombok/SuperBuilderWithGenerics2.java  |   1 +
 .../SuperBuilderWithGenericsAndToBuilder.java      |   1 +
 .../after-delombok/SuperBuilderWithPrefixes.java   |   1 +
 .../after-ecj/BuilderDefaultsWarnings.java         |   2 +
 .../after-ecj/BuilderSingularAnnotatedTypes.java   |   4 +
 ...lderSingularAnnotatedTypesWithSetterPrefix.java |   4 +
 .../after-ecj/BuilderSingularGuavaListsSets.java   |  10 ++
 .../after-ecj/BuilderSingularGuavaMaps.java        |   6 +
 .../resource/after-ecj/BuilderSingularLists.java   |   6 +
 .../resource/after-ecj/BuilderSingularMaps.java    |   8 ++
 .../BuilderSingularMapsWithSetterPrefix.java       |  78 +++++-----
 .../resource/after-ecj/BuilderSingularNoAuto.java  |   6 +
 .../BuilderSingularNoAutoWithSetterPrefix.java     |   6 +
 .../after-ecj/BuilderSingularNullBehavior1.java    | 154 ++++++++++++++++++++
 .../after-ecj/BuilderSingularRedirectToGuava.java  |   6 +
 .../resource/after-ecj/BuilderSingularSets.java    |   8 ++
 .../BuilderSingularSetsWithSetterPrefix.java       |   8 ++
 .../BuilderSingularToBuilderWithNull.java          |   2 +
 ...rSingularToBuilderWithNullWithSetterPrefix.java |   2 +
 .../BuilderSingularWildcardListsWithToBuilder.java |   4 +
 .../after-ecj/BuilderSingularWithPrefixes.java     |   2 +
 ...uilderSingularWithPrefixesWithSetterPrefix.java |   2 +
 .../resource/after-ecj/BuilderWithDeprecated.java  |   4 +
 .../resource/after-ecj/BuilderWithToBuilder.java   |   2 +
 .../after-ecj/CheckerFrameworkBuilder.java         |   2 +
 .../after-ecj/CheckerFrameworkSuperBuilder.java    |   2 +
 .../after-ecj/I2335_BuilderMultipleObtainVia.java  |   4 +-
 .../resource/after-ecj/SuperBuilderBasic.java      |   2 +
 .../after-ecj/SuperBuilderBasicToBuilder.java      |   2 +
 .../SuperBuilderSingularAnnotatedTypes.java        |   4 +
 .../SuperBuilderWithCustomBuilderMethod.java       |   2 +
 .../after-ecj/SuperBuilderWithGenerics.java        |   2 +
 .../after-ecj/SuperBuilderWithGenerics2.java       |   2 +
 .../SuperBuilderWithGenericsAndToBuilder.java      |   2 +
 .../after-ecj/SuperBuilderWithPrefixes.java        |   2 +
 .../BuilderSingularMapsWithSetterPrefix.java       |   1 +
 .../before/BuilderSingularNullBehavior1.java       |  13 ++
 79 files changed, 835 insertions(+), 108 deletions(-)
 create mode 100644 test/transform/resource/after-delombok/BuilderSingularNullBehavior1.java
 create mode 100644 test/transform/resource/after-ecj/BuilderSingularNullBehavior1.java
 create mode 100644 test/transform/resource/before/BuilderSingularNullBehavior1.java

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("name