Merge remote-tracking branch 'FabricMC/dev/0.7' into dev/0.7-forge

# Conflicts:
#	.github/workflows/test-push.yml
#	build.gradle
#	src/main/java/net/fabricmc/loom/configuration/CompileConfiguration.java
#	src/main/java/net/fabricmc/loom/configuration/ide/RunConfig.java
#	src/main/java/net/fabricmc/loom/configuration/providers/MinecraftProvider.java
#	src/main/java/net/fabricmc/loom/configuration/providers/mappings/MappingsProvider.java
#	src/main/java/net/fabricmc/loom/configuration/providers/minecraft/MinecraftMappedProvider.java
#	src/main/java/net/fabricmc/loom/configuration/providers/minecraft/assets/MinecraftAssetsProvider.java
#	src/main/java/net/fabricmc/loom/decompilers/fernflower/AbstractFernFlowerDecompiler.java
#	src/main/java/net/fabricmc/loom/decompilers/fernflower/ForkingJavaExec.java
#	src/main/java/net/fabricmc/loom/task/RemapJarTask.java
#	src/main/java/net/fabricmc/loom/util/GroovyXmlUtil.java
#	src/main/java/net/fabricmc/loom/util/HashedDownloadUtil.java
#	src/test/groovy/net/fabricmc/loom/BuildUtils.groovy

30 files changed, 1109 insertions, 557 deletions

diff --git a/src/main/java/net/fabricmc/loom/LoomGradleExtension.java b/src/main/java/net/fabricmc/loom/LoomGradleExtension.java
index 654f96c0..3fcefcea 100644
--- a/src/main/java/net/fabricmc/loom/LoomGradleExtension.java
+++ b/src/main/java/net/fabricmc/loom/LoomGradleExtension.java
@@ -501,6 +501,10 @@ public class LoomGradleExtension {
 		return new File(getProjectPersistentCache(), "log4j.xml");
 	}
 
+	public File getUnpickLoggingConfigFile() {
+		return new File(getProjectPersistentCache(), "unpick-logging.properties");
+	}
+
 	public ConfigurableFileCollection getLog4jConfigs() {
 		return log4jConfigs;
 	}
diff --git a/src/main/java/net/fabricmc/loom/build/nesting/JarNester.java b/src/main/java/net/fabricmc/loom/build/nesting/JarNester.java
new file mode 100644
index 00000000..6330b612
--- /dev/null
+++ b/src/main/java/net/fabricmc/loom/build/nesting/JarNester.java
@@ -0,0 +1,95 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.build.nesting;
+
+import java.io.File;
+import java.util.Collection;
+import java.util.zip.ZipEntry;
+
+import com.google.common.base.Preconditions;
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import org.gradle.api.logging.Logger;
+import org.zeroturnaround.zip.FileSource;
+import org.zeroturnaround.zip.ZipEntrySource;
+import org.zeroturnaround.zip.ZipUtil;
+import org.zeroturnaround.zip.transform.StringZipEntryTransformer;
+import org.zeroturnaround.zip.transform.ZipEntryTransformerEntry;
+
+import net.fabricmc.loom.LoomGradlePlugin;
+import net.fabricmc.loom.util.ModUtils;
+
+public class JarNester {
+	public static void nestJars(Collection<File> jars, File modJar, Logger logger) {
+		if (jars.isEmpty()) {
+			logger.debug("Nothing to nest into " + modJar.getName());
+			return;
+		}
+
+		Preconditions.checkArgument(ModUtils.isMod(modJar), "Cannot nest jars into none mod jar " + modJar.getName());
+
+		ZipUtil.addEntries(modJar, jars.stream().map(file -> new FileSource("META-INF/jars/" + file.getName(), file)).toArray(ZipEntrySource[]::new));
+
+		boolean didNest = ZipUtil.transformEntries(modJar, single(new ZipEntryTransformerEntry("fabric.mod.json", new StringZipEntryTransformer() {
+			@Override
+			protected String transform(ZipEntry zipEntry, String input) {
+				JsonObject json = LoomGradlePlugin.GSON.fromJson(input, JsonObject.class);
+				JsonArray nestedJars = json.getAsJsonArray("jars");
+
+				if (nestedJars == null || !json.has("jars")) {
+					nestedJars = new JsonArray();
+				}
+
+				for (File file : jars) {
+					String nestedJarPath = "META-INF/jars/" + file.getName();
+
+					for (JsonElement nestedJar : nestedJars) {
+						JsonObject jsonObject = nestedJar.getAsJsonObject();
+
+						if (jsonObject.has("file") && jsonObject.get("file").getAsString().equals(nestedJarPath)) {
+							throw new IllegalStateException("Cannot nest 2 jars at the same path: " + nestedJarPath);
+						}
+					}
+
+					JsonObject jsonObject = new JsonObject();
+					jsonObject.addProperty("file", nestedJarPath);
+					nestedJars.add(jsonObject);
+
+					logger.debug("Nested " + nestedJarPath + " into " + modJar.getName());
+				}
+
+				json.add("jars", nestedJars);
+
+				return LoomGradlePlugin.GSON.toJson(json);
+			}
+		})));
+		Preconditions.checkArgument(didNest, "Failed to nest jars into " + modJar.getName());
+	}
+
+	private static ZipEntryTransformerEntry[] single(ZipEntryTransformerEntry element) {
+		return new ZipEntryTransformerEntry[]{element};
+	}
+}
diff --git a/src/main/java/net/fabricmc/loom/build/nesting/MergedNestedJarProvider.java b/src/main/java/net/fabricmc/loom/build/nesting/MergedNestedJarProvider.java
new file mode 100644
index 00000000..566002d4
--- /dev/null
+++ b/src/main/java/net/fabricmc/loom/build/nesting/MergedNestedJarProvider.java
@@ -0,0 +1,46 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.build.nesting;
+
+import java.io.File;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.stream.Collectors;
+
+public class MergedNestedJarProvider implements NestedJarProvider {
+	private final NestedJarProvider[] parents;
+
+	public MergedNestedJarProvider(NestedJarProvider... parents) {
+		this.parents = parents;
+	}
+
+	@Override
+	public Collection<File> provide() {
+		return Arrays.stream(parents)
+				.map(NestedJarProvider::provide)
+				.flatMap(Collection::stream)
+				.collect(Collectors.toList());
+	}
+}
diff --git a/src/main/java/net/fabricmc/loom/build/NestedJars.java b/src/main/java/net/fabricmc/loom/build/nesting/NestedDependencyProvider.java
index c88c4487..dbca51ed 100644
--- a/src/main/java/net/fabricmc/loom/build/NestedJars.java
+++ b/src/main/java/net/fabricmc/loom/build/nesting/NestedDependencyProvider.java
@@ -22,22 +22,18 @@
  * SOFTWARE.
  */
 
-package net.fabricmc.loom.build;
+package net.fabricmc.loom.build.nesting;
 
 import java.io.File;
 import java.io.IOException;
-import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Locale;
 import java.util.Set;
 import java.util.stream.Collectors;
-import java.util.zip.ZipEntry;
 
-import com.google.gson.JsonArray;
 import com.google.gson.JsonObject;
 import org.apache.commons.io.FileUtils;
 import org.gradle.api.Project;
@@ -50,68 +46,64 @@ import org.gradle.api.artifacts.ResolvedArtifact;
 import org.gradle.api.artifacts.ResolvedConfiguration;
 import org.gradle.api.artifacts.ResolvedDependency;
 import org.gradle.api.tasks.bundling.AbstractArchiveTask;
-import org.zeroturnaround.zip.FileSource;
-import org.zeroturnaround.zip.ZipEntrySource;
 import org.zeroturnaround.zip.ZipUtil;
-import org.zeroturnaround.zip.transform.StringZipEntryTransformer;
-import org.zeroturnaround.zip.transform.ZipEntryTransformerEntry;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.task.RemapJarTask;
 import net.fabricmc.loom.util.Constants;
 
-public class NestedJars {
-	public static boolean addNestedJars(Project project, Path modJarPath) {
-		List<File> containedJars = getContainedJars(project);
+public final class NestedDependencyProvider implements NestedJarProvider {
+	final Project project;
+	final List<DependencyInfo<?>> files;
 
-		if (containedJars.isEmpty()) {
-			return false;
-		}
+	private NestedDependencyProvider(Project project, List<DependencyInfo<?>> files) {
+		this.project = project;
+		this.files = files;
+	}
 
-		File modJar = modJarPath.toFile();
+	public static NestedDependencyProvider createNestedDependencyProviderFromConfiguration(Project project, Configuration configuration) {
+		List<DependencyInfo<?>> fileList = new ArrayList<>();
+		Set<String> visited = new HashSet<>();
 
-		ZipUtil.addOrReplaceEntries(modJar, containedJars.stream().map(file -> new FileSource("META-INF/jars/" + file.getName(), file)).toArray(ZipEntrySource[]::new));
+		fileList.addAll(populateProjectDependencies(configuration, visited));
+		fileList.addAll(populateResolvedDependencies(configuration, visited));
 
-		return ZipUtil.transformEntries(modJar, single(new ZipEntryTransformerEntry("fabric.mod.json", new StringZipEntryTransformer() {
-			@Override
-			protected String transform(ZipEntry zipEntry, String input) {
-				JsonObject json = LoomGradlePlugin.GSON.fromJson(input, JsonObject.class);
-				JsonArray nestedJars = json.getAsJsonArray("jars");
+		return new NestedDependencyProvider(project, fileList);
+	}
 
-				if (nestedJars == null || !json.has("jars")) {
-					nestedJars = new JsonArray();
-				}
+	// Looks for any deps that require a sub project to be built first
+	public static List<RemapJarTask> getRequiredTasks(Project project) {
+		List<RemapJarTask> remapTasks = new ArrayList<>();
 
-				for (File file : containedJars) {
-					JsonObject jsonObject = new JsonObject();
-					jsonObject.addProperty("file", "META-INF/jars/" + file.getName());
-					nestedJars.add(jsonObject);
-				}
+		Configuration configuration = project.getConfigurations().getByName(Constants.Configurations.INCLUDE);
+		DependencySet dependencies = configuration.getDependencies();
 
-				json.add("jars", nestedJars);
+		for (Dependency dependency : dependencies) {
+			if (dependency instanceof ProjectDependency) {
+				ProjectDependency projectDependency = (ProjectDependency) dependency;
+				Project dependencyProject = projectDependency.getDependencyProject();
 
-				return LoomGradlePlugin.GSON.toJson(json);
+				for (Task task : dependencyProject.getTasksByName("remapJar", false)) {
+					if (task instanceof RemapJarTask) {
+						remapTasks.add((RemapJarTask) task);
+					}
+				}
 			}
-		})));
-	}
-
-	private static List<File> getContainedJars(Project project) {
-		List<File> fileList = new ArrayList<>();
+		}
 
-		Configuration configuration = project.getConfigurations().getByName(Constants.Configurations.INCLUDE);
-		ResolvedConfiguration resolvedConfiguration = configuration.getResolvedConfiguration();
-		Set<ResolvedDependency> dependencies = resolvedConfiguration.getFirstLevelModuleDependencies();
+		return remapTasks;
+	}
 
-		// Bit ugly doing this, id guess there is a better way but this works.
-		Set<String> projectDeps = new HashSet<>();
+	private static List<DependencyInfo<ProjectDependency>> populateProjectDependencies(Configuration configuration, Set<String> visited) {
+		List<DependencyInfo<ProjectDependency>> fileList = new ArrayList<>();
 
 		for (Dependency dependency : configuration.getDependencies()) {
 			if (dependency instanceof ProjectDependency) {
 				ProjectDependency projectDependency = (ProjectDependency) dependency;
 				Project dependencyProject = projectDependency.getDependencyProject();
 
-				projectDeps.add(dependency.getGroup() + ":" + dependency.getName() + ":" + dependency.getVersion());
+				visited.add(dependency.getGroup() + ":" + dependency.getName() + ":" + dependency.getVersion());
 
 				// TODO change this to allow just normal jar tasks, so a project can have a none loom sub project
 				Collection<Task> remapJarTasks = dependencyProject.getTasksByName("remapJar", false);
@@ -119,82 +111,53 @@ public class NestedJars {
 
 				for (Task task : remapJarTasks.isEmpty() ? jarTasks : remapJarTasks) {
 					if (task instanceof RemapJarTask) {
-						fileList.addAll(prepareForNesting(
-								Collections.singleton(((RemapJarTask) task).getArchivePath()),
-								projectDependency,
-								new ProjectDependencyMetaExtractor(),
-								project
-						));
+						File file = ((RemapJarTask) task).getArchivePath();
+						fileList.add(new DependencyInfo<>(projectDependency, new ProjectDependencyMetaExtractor(), file));
 					} else if (task instanceof AbstractArchiveTask) {
-						fileList.addAll(prepareForNesting(
-								Collections.singleton(((AbstractArchiveTask) task).getArchivePath()),
-								projectDependency,
-								new ProjectDependencyMetaExtractor(),
-								project
-						));
+						File file = ((AbstractArchiveTask) task).getArchivePath();
+						fileList.add(new DependencyInfo<>(projectDependency, new ProjectDependencyMetaExtractor(), file));
 					}
 				}
 			}
 		}
 
+		return fileList;
+	}
+
+	private static List<DependencyInfo<ResolvedDependency>> populateResolvedDependencies(Configuration configuration, Set<String> visited) {
+		ResolvedConfiguration resolvedConfiguration = configuration.getResolvedConfiguration();
+		Set<ResolvedDependency> dependencies = resolvedConfiguration.getFirstLevelModuleDependencies();
+
+		List<DependencyInfo<ResolvedDependency>> fileList = new ArrayList<>();
+
 		for (ResolvedDependency dependency : dependencies) {
-			if (projectDeps.contains(dependency.getModuleGroup() + ":" + dependency.getModuleName() + ":" + dependency.getModuleVersion())) {
+			if (visited.contains(dependency.getModuleGroup() + ":" + dependency.getModuleName() + ":" + dependency.getModuleVersion())) {
 				continue;
-			} else {
-				fileList.addAll(prepareForNesting(
-						dependency
-								.getModuleArtifacts()
-								.stream()
-								.map(ResolvedArtifact::getFile)
-								.collect(Collectors.toSet()),
-						dependency,
-						new ResolvedDependencyMetaExtractor(),
-						project
-				));
 			}
-		}
 
-		for (File file : fileList) {
-			if (!file.exists()) {
-				throw new RuntimeException("Failed to include nested jars, as it could not be found @ " + file.getAbsolutePath());
-			}
+			List<File> files = dependency
+					.getModuleArtifacts()
+					.stream()
+					.map(ResolvedArtifact::getFile)
+					.collect(Collectors.toList());
 
-			if (file.isDirectory() || !file.getName().endsWith(".jar")) {
-				throw new RuntimeException("Failed to include nested jars, as file was not a jar: " + file.getAbsolutePath());
+			for (File file : files) {
+				fileList.add(new DependencyInfo<>(dependency, new ResolvedDependencyMetaExtractor(), file));
 			}
 		}
 
 		return fileList;
 	}
 
-	// Looks for any deps that require a sub project to be built first
-	public static List<RemapJarTask> getRequiredTasks(Project project) {
-		List<RemapJarTask> remapTasks = new ArrayList<>();
-
-		Configuration configuration = project.getConfigurations().getByName(Constants.Configurations.INCLUDE);
-		DependencySet dependencies = configuration.getDependencies();
-
-		for (Dependency dependency : dependencies) {
-			if (dependency instanceof ProjectDependency) {
-				ProjectDependency projectDependency = (ProjectDependency) dependency;
-				Project dependencyProject = projectDependency.getDependencyProject();
-
-				for (Task task : dependencyProject.getTasksByName("remapJar", false)) {
-					if (task instanceof RemapJarTask) {
-						remapTasks.add((RemapJarTask) task);
-					}
-				}
-			}
-		}
+	@Override
+	public List<File> provide() {
+		List<File> fileList = new ArrayList<>();
 
-		return remapTasks;
-	}
+		for (DependencyInfo<?> metaFile : files) {
+			metaFile.validateInputs();
 
-	//This is a good place to do pre-nesting operations, such as adding a fabric.mod.json to a library
-	private static <D> List<File> prepareForNesting(Set<File> files, D dependency, DependencyMetaExtractor<D> metaExtractor, Project project) {
-		List<File> fileList = new ArrayList<>();
+			File file = metaFile.file;
 
-		for (File file : files) {
 			//A lib that doesnt have a mod.json, we turn it into a fake mod
 			if (!ZipUtil.containsEntry(file, "fabric.mod.json")) {
 				LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
@@ -216,7 +179,7 @@ public class NestedJars {
 					throw new RuntimeException("Failed to copy file", e);
 				}
 
-				ZipUtil.addEntry(tempFile, "fabric.mod.json", getMod(dependency, metaExtractor).getBytes());
+				ZipUtil.addEntry(tempFile, "fabric.mod.json", generateModForDependency(metaFile).getBytes());
 				fileList.add(tempFile);
 			} else {
 				// Default copy the jar right in
@@ -228,7 +191,10 @@ public class NestedJars {
 	}
 
 	// Generates a barebones mod for a dependency
-	private static <D> String getMod(D dependency, DependencyMetaExtractor<D> metaExtractor) {
+	private static <D> String generateModForDependency(DependencyInfo<D> info) {
+		DependencyMetaExtractor<D> metaExtractor = info.metaExtractor;
+		D dependency = info.dependency;
+
 		JsonObject jsonObject = new JsonObject();
 		jsonObject.addProperty("schemaVersion", 1);
 		jsonObject.addProperty("id", (metaExtractor.group(dependency) + "_" + metaExtractor.name(dependency)).replaceAll("\\.", "_").toLowerCase(Locale.ENGLISH));
@@ -242,8 +208,26 @@ public class NestedJars {
 		return LoomGradlePlugin.GSON.toJson(jsonObject);
 	}
 
-	private static ZipEntryTransformerEntry[] single(ZipEntryTransformerEntry element) {
-		return new ZipEntryTransformerEntry[]{element};
+	private static class DependencyInfo<D> {
+		final D dependency;
+		final DependencyMetaExtractor<D> metaExtractor;
+		final File file;
+
+		DependencyInfo(D dependency, DependencyMetaExtractor<D> metaExtractor, File file) {
+			this.dependency = dependency;
+			this.metaExtractor = metaExtractor;
+			this.file = file;
+		}
+
+		public void validateInputs() {
+			if (!file.exists()) {
+				throw new RuntimeException("Failed to include nested jars, as it could not be found @ " + file.getAbsolutePath());
+			}
+
+			if (file.isDirectory() || !file.getName().endsWith(".jar")) {
+				throw new RuntimeException("Failed to include nested jars, as file was not a jar: " + file.getAbsolutePath());
+			}
+		}
 	}
 
 	private interface DependencyMetaExtractor<D> {
diff --git a/src/main/java/net/fabricmc/loom/build/nesting/NestedJarPathProvider.java b/src/main/java/net/fabricmc/loom/build/nesting/NestedJarPathProvider.java
new file mode 100644
index 00000000..badb2656
--- /dev/null
+++ b/src/main/java/net/fabricmc/loom/build/nesting/NestedJarPathProvider.java
@@ -0,0 +1,67 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.build.nesting;
+
+import java.io.File;
+import java.util.Collection;
+import java.util.Set;
+
+import com.google.common.base.Preconditions;
+import org.gradle.api.Project;
+
+import net.fabricmc.loom.util.ModUtils;
+
+public final class NestedJarPathProvider implements NestedJarProvider {
+	private final Set<Object> nestedPaths;
+	private Set<File> files = null;
+	public NestedJarPathProvider(Set<Object> nestedPaths) {
+		this.nestedPaths = nestedPaths;
+	}
+
+	private Set<File> resolve(Project project) {
+		return project.files(nestedPaths).getFiles();
+	}
+
+	@Override
+	public void prepare(Project project) {
+		if (files == null) {
+			files = resolve(project);
+		}
+	}
+
+	@Override
+	public Collection<File> provide() {
+		validateFiles();
+		return files;
+	}
+
+	private void validateFiles() {
+		for (File file : files) {
+			Preconditions.checkArgument(file.getName().endsWith(".jar"), String.format("Tried to nest %s but it is not a jar", file.getAbsolutePath()));
+			Preconditions.checkArgument(file.exists(), String.format("Tried to nest jar %s but it does not exist", file.getAbsolutePath()));
+			Preconditions.checkArgument(ModUtils.isMod(file), String.format("Cannot use nest none mod jar %s", file.getAbsolutePath()));
+		}
+	}
+}
diff --git a/src/main/java/net/fabricmc/loom/build/nesting/NestedJarProvider.java b/src/main/java/net/fabricmc/loom/build/nesting/NestedJarProvider.java
new file mode 100644
index 00000000..3ddbae31
--- /dev/null
+++ b/src/main/java/net/fabricmc/loom/build/nesting/NestedJarProvider.java
@@ -0,0 +1,40 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.build.nesting;
+
+import java.io.File;
+import java.util.Collection;
+
+import org.gradle.api.Project;
+import org.jetbrains.annotations.ApiStatus;
+
+@ApiStatus.Internal
+public interface NestedJarProvider {
+	// provide all the files to be included, they should already be resolved but can be transformed here
+	Collection<File> provide();
+
+	// Setup the files ready to be provided
+	default void prepare(Project project) { }
+}
diff --git a/src/main/java/net/fabricmc/loom/configuration/CompileConfiguration.java b/src/main/java/net/fabricmc/loom/configuration/CompileConfiguration.java
index 01310e6d..23de41b2 100644
--- a/src/main/java/net/fabricmc/loom/configuration/CompileConfiguration.java
+++ b/src/main/java/net/fabricmc/loom/configuration/CompileConfiguration.java
@@ -24,17 +24,8 @@
 
 package net.fabricmc.loom.configuration;
 
-import java.io.IOException;
-import java.util.ArrayList;
-import java.util.List;
-
-import com.google.common.collect.ImmutableMap;
-import org.gradle.api.Action;
 import org.gradle.api.Project;
-import org.gradle.api.Task;
-import org.gradle.api.UnknownTaskException;
 import org.gradle.api.artifacts.Configuration;
-import org.gradle.api.artifacts.repositories.MavenArtifactRepository;
 import org.gradle.api.plugins.JavaPlugin;
 import org.gradle.api.plugins.JavaPluginConvention;
 import org.gradle.api.tasks.SourceSet;
@@ -43,8 +34,6 @@ import org.gradle.api.tasks.bundling.Jar;
 import org.gradle.api.tasks.javadoc.Javadoc;
 
 import net.fabricmc.loom.LoomGradleExtension;
-import net.fabricmc.loom.build.JarRemapper;
-import net.fabricmc.loom.build.NestedJars;
 import net.fabricmc.loom.build.mixin.JavaApInvoker;
 import net.fabricmc.loom.build.mixin.KaptApInvoker;
 import net.fabricmc.loom.build.mixin.ScalaApInvoker;
@@ -58,17 +47,8 @@ import net.fabricmc.loom.configuration.providers.forge.McpConfigProvider;
 import net.fabricmc.loom.configuration.providers.forge.PatchProvider;
 import net.fabricmc.loom.configuration.providers.forge.SrgProvider;
 import net.fabricmc.loom.configuration.providers.mappings.MappingsProvider;
-import net.fabricmc.loom.task.AbstractLoomTask;
-import net.fabricmc.loom.task.GenVsCodeProjectTask;
-import net.fabricmc.loom.task.RemapAllSourcesTask;
-import net.fabricmc.loom.task.RemapJarTask;
-import net.fabricmc.loom.task.RemapSourcesJarTask;
 import net.fabricmc.loom.util.Constants;
-import net.fabricmc.loom.util.SourceRemapper;
 
-/**
- * Add Minecraft dependencies to compile time.
- */
 public final class CompileConfiguration {
 	private CompileConfiguration() {
 	}
@@ -121,9 +101,13 @@ public final class CompileConfiguration {
 		Configuration includeConfig = project.getConfigurations().maybeCreate(Constants.Configurations.INCLUDE);
 		includeConfig.setTransitive(false); // Dont get transitive deps
 
+		project.getConfigurations().maybeCreate(Constants.Configurations.MAPPING_CONSTANTS);
+		extendsFrom(JavaPlugin.COMPILE_ONLY_CONFIGURATION_NAME, Constants.Configurations.MAPPING_CONSTANTS, project);
+
 		project.getConfigurations().maybeCreate(Constants.Configurations.MAPPINGS);
 		project.getConfigurations().maybeCreate(Constants.Configurations.MAPPINGS_FINAL);
 		project.getConfigurations().maybeCreate(Constants.Configurations.LOOM_DEVELOPMENT_DEPENDENCIES);
+		project.getConfigurations().maybeCreate(Constants.Configurations.UNPICK_CLASSPATH);
 
 		for (RemappedConfigurationEntry entry : Constants.MOD_COMPILE_ENTRIES) {
 			Configuration compileModsConfig = project.getConfigurations().maybeCreate(entry.getSourceConfiguration());
@@ -152,75 +136,18 @@ public final class CompileConfiguration {
 		extendsFrom(JavaPlugin.RUNTIME_CLASSPATH_CONFIGURATION_NAME, Constants.Configurations.LOOM_DEVELOPMENT_DEPENDENCIES, project);
 	}
 
-	/**
-	 * Permit to add a Maven repository to a target project.
-	 *
-	 * @param target The target project
-	 * @param name   The name of the repository
-	 * @param url    The URL of the repository
-	 * @return An object containing the name and the URL of the repository that can be modified later
-	 */
-	public static MavenArtifactRepository addMavenRepo(Project target, final String name, final String url) {
-		return addMavenRepo(target, name, url, repo -> {
-		});
-	}
-
-	public static MavenArtifactRepository addMavenRepo(Project target, final String name, final String url, final Action<MavenArtifactRepository> action) {
-		return target.getRepositories().maven(repo -> {
-			repo.setName(name);
-			repo.setUrl(url);
-			action.execute(repo);
-		});
-	}
-
-	public static void configureCompile(Project project) {
-		JavaPluginConvention javaModule = (JavaPluginConvention) project.getConvention().getPlugins().get("java");
+	public static void configureCompile(Project p) {
+		JavaPluginConvention javaModule = (JavaPluginConvention) p.getConvention().getPlugins().get("java");
 
 		SourceSet main = javaModule.getSourceSets().getByName(SourceSet.MAIN_SOURCE_SET_NAME);
 
-		Javadoc javadoc = (Javadoc) project.getTasks().getByName(JavaPlugin.JAVADOC_TASK_NAME);
+		Javadoc javadoc = (Javadoc) p.getTasks().getByName(JavaPlugin.JAVADOC_TASK_NAME);
 		javadoc.setClasspath(main.getOutput().plus(main.getCompileClasspath()));
 
-		project.afterEvaluate(project1 -> {
-			LoomGradleExtension extension = project1.getExtensions().getByType(LoomGradleExtension.class);
-
-			project1.getRepositories().flatDir(flatDirectoryArtifactRepository -> {
-				flatDirectoryArtifactRepository.dir(extension.getRootProjectBuildCache());
-				flatDirectoryArtifactRepository.setName("UserLocalCacheFiles");
-			});
-
-			project1.getRepositories().maven(mavenArtifactRepository -> {
-				mavenArtifactRepository.setUrl(extension.getRemappedModCache());
-				mavenArtifactRepository.setName("UserLocalRemappedMods");
-			});
-
-			project1.getRepositories().maven(mavenArtifactRepository -> {
-				mavenArtifactRepository.setName("Fabric");
-				mavenArtifactRepository.setUrl("https://maven.fabricmc.net/");
-			});
-
-			project1.getRepositories().maven(mavenArtifactRepository -> {
-				mavenArtifactRepository.setName("Mojang");
-				mavenArtifactRepository.setUrl("https://libraries.minecraft.net/");
-			});
-
-			project1.getRepositories().maven(mavenArtifactRepository -> {
-				mavenArtifactRepository.setName("Forge");
-				mavenArtifactRepository.setUrl("https://files.minecraftforge.net/maven/");
-
-				mavenArtifactRepository.metadataSources(sources -> {
-					sources.mavenPom();
-
-					try {
-						MavenArtifactRepository.MetadataSources.class.getDeclaredMethod("ignoreGradleMetadataRedirection")
-								.invoke(sources);
-					} catch (Throwable ignored) {
-						// Method not available
-					}
-				});
-			});
+		p.afterEvaluate(project -> {
+			LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
 
-			project1.getRepositories().mavenCentral();
+			MavenConfiguration.setup(project);
 
 			LoomDependencyManager dependencyManager = new LoomDependencyManager();
 			extension.setDependencyManager(dependencyManager);
@@ -245,118 +172,20 @@ public final class CompileConfiguration {
 			dependencyManager.addProvider(new MappingsProvider(project));
 			dependencyManager.addProvider(new LaunchProvider(project));
 
-			dependencyManager.handleDependencies(project1);
+			dependencyManager.handleDependencies(project);
 
-			project1.getTasks().getByName("idea").finalizedBy(project1.getTasks().getByName("genIdeaWorkspace"));
-			project1.getTasks().getByName("eclipse").finalizedBy(project1.getTasks().getByName("genEclipseRuns"));
-			project1.getTasks().getByName("cleanEclipse").finalizedBy(project1.getTasks().getByName("cleanEclipseRuns"));
+			project.getTasks().getByName("idea").finalizedBy(project.getTasks().getByName("genIdeaWorkspace"));
+			project.getTasks().getByName("eclipse").finalizedBy(project.getTasks().getByName("genEclipseRuns"));
+			project.getTasks().getByName("cleanEclipse").finalizedBy(project.getTasks().getByName("cleanEclipseRuns"));
 
-			SetupIntelijRunConfigs.setup(project1);
+			SetupIntelijRunConfigs.setup(project);
 			GenVsCodeProjectTask.generate(project1);
 
 			// Enables the default mod remapper
 			if (extension.remapMod) {
-				AbstractArchiveTask jarTask = (AbstractArchiveTask) project1.getTasks().getByName("jar");
-				RemapJarTask remapJarTask = (RemapJarTask) project1.getTasks().findByName("remapJar");
-
-				assert remapJarTask != null;
-
-				if (!remapJarTask.getInput().isPresent()) {
-					jarTask.setClassifier("dev");
-					remapJarTask.setClassifier("");
-					remapJarTask.getInput().set(jarTask.getArchivePath());
-				}
-
-				if (extension.isForge()) {
-					remapJarTask.getToM().set("srg");
-					((Jar) jarTask).manifest(manifest -> {
-						List<String> configs = new ArrayList<>();
-
-						if (extension.mixinConfig != null) {
-							configs.add(extension.mixinConfig);
-						}
-
-						if (extension.mixinConfigs != null) {
-							configs.addAll(extension.mixinConfigs);
-						}
-
-						manifest.attributes(ImmutableMap.of("MixinConfigs", String.join(",", configs)));
-					});
-				}
-
-				extension.getUnmappedModCollection().from(jarTask);
-				remapJarTask.getAddNestedDependencies().set(true);
-				remapJarTask.getRemapAccessWidener().set(true);
-
-				project1.getArtifacts().add("archives", remapJarTask);
-				remapJarTask.dependsOn(jarTask);
-				project1.getTasks().getByName("build").dependsOn(remapJarTask);
-
-				project.getTasks().withType(RemapJarTask.class).forEach(task -> {
-					if (task.getAddNestedDependencies().getOrElse(false)) {
-						NestedJars.getRequiredTasks(project1).forEach(task::dependsOn);
-					}
-				});
-
-				SourceRemapper remapper = null;
-				Task parentTask = project1.getTasks().getByName("build");
-
-				if (extension.isShareCaches()) {
-					Project rootProject = project.getRootProject();
-
-					if (extension.isRootProject()) {
-						SourceRemapper sourceRemapper = new SourceRemapper(rootProject, false);
-						JarRemapper jarRemapper = new JarRemapper();
-
-						remapJarTask.jarRemapper = jarRemapper;
-
-						rootProject.getTasks().register("remapAllSources", RemapAllSourcesTask.class, task -> {
-							task.sourceRemapper = sourceRemapper;
-							task.doLast(t -> sourceRemapper.remapAll());
-						});
-
-						parentTask = rootProject.getTasks().getByName("remapAllSources");
-
-						rootProject.getTasks().register("remapAllJars", AbstractLoomTask.class, task -> {
-							task.doLast(t -> {
-								try {
-									jarRemapper.remap(rootProject);
-								} catch (IOException e) {
-									throw new RuntimeException("Failed to remap jars", e);
-								}
-							});
-						});
-					} else {
-						parentTask = rootProject.getTasks().getByName("remapAllSources");
-						remapper = ((RemapAllSourcesTask) parentTask).sourceRemapper;
-
-						remapJarTask.jarRemapper = ((RemapJarTask) rootProject.getTasks().getByName("remapJar")).jarRemapper;
-
-						project1.getTasks().getByName("build").dependsOn(parentTask);
-						project1.getTasks().getByName("build").dependsOn(rootProject.getTasks().getByName("remapAllJars"));
-						rootProject.getTasks().getByName("remapAllJars").dependsOn(project1.getTasks().getByName("remapJar"));
-					}
-				}
-
-				try {
-					AbstractArchiveTask sourcesTask = (AbstractArchiveTask) project1.getTasks().getByName("sourcesJar");
-
-					RemapSourcesJarTask remapSourcesJarTask = (RemapSourcesJarTask) project1.getTasks().findByName("remapSourcesJar");
-					remapSourcesJarTask.setInput(sourcesTask.getArchivePath());
-					remapSourcesJarTask.setOutput(sourcesTask.getArchivePath());
-					remapSourcesJarTask.doLast(task -> project1.getArtifacts().add("archives", remapSourcesJarTask.getOutput()));
-					remapSourcesJarTask.dependsOn(project1.getTasks().getByName("sourcesJar"));
-
-					if (extension.isShareCaches()) {
-						remapSourcesJarTask.setSourceRemapper(remapper);
-					}
-
-					parentTask.dependsOn(remapSourcesJarTask);
-				} catch (UnknownTaskException ignored) {
-					// pass
-				}
+				RemapConfiguration.setupDefaultRemap(project);
 			} else {
-				AbstractArchiveTask jarTask = (AbstractArchiveTask) project1.getTasks().getByName("jar");
+				AbstractArchiveTask jarTask = (AbstractArchiveTask) project.getTasks().getByName("jar");
 				extension.getUnmappedModCollection().from(jarTask);
 			}
 
@@ -379,7 +208,7 @@ public final class CompileConfiguration {
 			}
 		});
 
-		if (project.getPluginManager().hasPlugin("org.jetbrains.kotlin.kapt")) {
+		if (p.getPluginManager().hasPlugin("org.jetbrains.kotlin.kapt")) {
 			// If loom is applied after kapt, then kapt will use the AP arguments too early for loom to pass the arguments we need for mixin.
 			throw new IllegalArgumentException("fabric-loom must be applied BEFORE kapt in the plugins { } block.");
 		}
diff --git a/src/main/java/net/fabricmc/loom/configuration/MavenConfiguration.java b/src/main/java/net/fabricmc/loom/configuration/MavenConfiguration.java
new file mode 100644
index 00000000..2fb2ae7c
--- /dev/null
+++ b/src/main/java/net/fabricmc/loom/configuration/MavenConfiguration.java
@@ -0,0 +1,57 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.configuration;
+
+import org.gradle.api.Project;
+
+import net.fabricmc.loom.LoomGradleExtension;
+
+public class MavenConfiguration {
+	public static void setup(Project project) {
+		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+
+		project.getRepositories().flatDir(repo -> {
+			repo.setName("UserLocalCacheFiles");
+			repo.dir(extension.getRootProjectBuildCache());
+		});
+
+		project.getRepositories().maven(repo -> {
+			repo.setName("UserLocalRemappedMods");
+			repo.setUrl(extension.getRemappedModCache());
+		});
+
+		project.getRepositories().maven(repo -> {
+			repo.setName("Fabric");
+			repo.setUrl("https://maven.fabricmc.net/");
+		});
+
+		project.getRepositories().maven(repo -> {
+			repo.setName("Mojang");
+			repo.setUrl("https://libraries.minecraft.net/");
+		});
+
+		project.getRepositories().mavenCentral();
+	}
+}
diff --git a/src/main/java/net/fabricmc/loom/configuration/RemapConfiguration.java b/src/main/java/net/fabricmc/loom/configuration/RemapConfiguration.java
new file mode 100644
index 00000000..7534c27b
--- /dev/null
+++ b/src/main/java/net/fabricmc/loom/configuration/RemapConfiguration.java
@@ -0,0 +1,159 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.configuration;
+
+import java.io.IOException;
+
+import com.google.common.base.Preconditions;
+import org.gradle.api.Project;
+import org.gradle.api.Task;
+import org.gradle.api.UnknownTaskException;
+import org.gradle.api.plugins.JavaPlugin;
+import org.gradle.api.tasks.bundling.AbstractArchiveTask;
+import org.jetbrains.annotations.ApiStatus;
+
+import net.fabricmc.loom.LoomGradleExtension;
+import net.fabricmc.loom.build.JarRemapper;
+import net.fabricmc.loom.build.nesting.NestedDependencyProvider;
+import net.fabricmc.loom.task.AbstractLoomTask;
+import net.fabricmc.loom.task.RemapAllSourcesTask;
+import net.fabricmc.loom.task.RemapJarTask;
+import net.fabricmc.loom.task.RemapSourcesJarTask;
+import net.fabricmc.loom.util.SourceRemapper;
+
+public class RemapConfiguration {
+	private static final String DEFAULT_JAR_TASK_NAME = JavaPlugin.JAR_TASK_NAME;
+	private static final String DEFAULT_SOURCES_JAR_TASK_NAME = "sourcesJar";
+	private static final String DEFAULT_REMAP_JAR_TASK_NAME = "remapJar";
+	private static final String DEFAULT_REMAP_SOURCES_JAR_TASK_NAME = "remapSourcesJar";
+	private static final String DEFAULT_REMAP_ALL_JARS_TASK_NAME = "remapAllJars";
+	private static final String DEFAULT_REMAP_ALL_SOURCES_TASK_NAME = "remapAllSources";
+
+	public static void setupDefaultRemap(Project project) {
+		setupRemap(project, true, DEFAULT_JAR_TASK_NAME, DEFAULT_SOURCES_JAR_TASK_NAME, DEFAULT_REMAP_JAR_TASK_NAME, DEFAULT_REMAP_SOURCES_JAR_TASK_NAME, DEFAULT_REMAP_ALL_JARS_TASK_NAME, DEFAULT_REMAP_ALL_SOURCES_TASK_NAME);
+	}
+
+	@ApiStatus.Experimental // This is only an api if you squint really hard, expect it to explode every 5 mins. If you must call in afterEvaluate on all projects
+	public static void setupRemap(Project project, String jarTaskName, String sourcesJarTaskName, String remapJarTaskName, String remapSourcesJarTaskName, String remapAllJarsTaskName, String remapAllSourcesTaskName) {
+		setupRemap(project, false, jarTaskName, sourcesJarTaskName, remapJarTaskName, remapSourcesJarTaskName, remapAllJarsTaskName, remapAllSourcesTaskName);
+	}
+
+	// isDefaultRemap is set to true for the standard remap task, some defaults are left out when this is false.
+	private static void setupRemap(Project project, boolean isDefaultRemap, String jarTaskName, String sourcesJarTaskName, String remapJarTaskName, String remapSourcesJarTaskName, String remapAllJarsTaskName, String remapAllSourcesTaskName) {
+		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		AbstractArchiveTask jarTask = (AbstractArchiveTask) project.getTasks().getByName(jarTaskName);
+		RemapJarTask remapJarTask = (RemapJarTask) project.getTasks().findByName(remapJarTaskName);
+
+		assert remapJarTask != null;
+
+		if (!remapJarTask.getInput().isPresent() && isDefaultRemap) {
+			jarTask.setClassifier("dev");
+			remapJarTask.setClassifier("");
+			remapJarTask.getInput().set(jarTask.getArchivePath());
+		}
+
+		if (isDefaultRemap) {
+			extension.getUnmappedModCollection().from(jarTask);
+			remapJarTask.getAddNestedDependencies().set(true);
+			remapJarTask.getRemapAccessWidener().set(true);
+
+			project.getArtifacts().add("archives", remapJarTask);
+		}
+
+		remapJarTask.dependsOn(jarTask);
+		project.getTasks().getByName("build").dependsOn(remapJarTask);
+
+		// TODO this might be wrong?
+		project.getTasks().withType(RemapJarTask.class).forEach(task -> {
+			if (task.getAddNestedDependencies().getOrElse(false)) {
+				NestedDependencyProvider.getRequiredTasks(project).forEach(task::dependsOn);
+			}
+		});
+
+		SourceRemapper remapper = null;
+		// TODO what is this for?
+		Task parentTask = project.getTasks().getByName("build");
+
+		if (extension.isShareCaches()) {
+			Project rootProject = project.getRootProject();
+
+			if (extension.isRootProject()) {
+				SourceRemapper sourceRemapper = new SourceRemapper(rootProject, false);
+				JarRemapper jarRemapper = new JarRemapper();
+
+				remapJarTask.jarRemapper = jarRemapper;
+
+				rootProject.getTasks().register(remapAllSourcesTaskName, RemapAllSourcesTask.class, task -> {
+					task.sourceRemapper = sourceRemapper;
+					task.doLast(t -> sourceRemapper.remapAll());
+				});
+
+				parentTask = rootProject.getTasks().getByName(remapAllSourcesTaskName);
+
+				rootProject.getTasks().register(remapAllJarsTaskName, AbstractLoomTask.class, task -> {
+					task.doLast(t -> {
+						try {
+							jarRemapper.remap();
+						} catch (IOException e) {
+							throw new RuntimeException("Failed to remap jars", e);
+						}
+					});
+				});
+			} else {
+				parentTask = rootProject.getTasks().getByName(remapAllSourcesTaskName);
+				remapper = ((RemapAllSourcesTask) parentTask).sourceRemapper;
+				Preconditions.checkNotNull(remapper);
+
+				remapJarTask.jarRemapper = ((RemapJarTask) rootProject.getTasks().getByName(remapJarTaskName)).jarRemapper;
+
+				project.getTasks().getByName("build").dependsOn(parentTask);
+				project.getTasks().getByName("build").dependsOn(rootProject.getTasks().getByName(remapAllJarsTaskName));
+				rootProject.getTasks().getByName(remapAllJarsTaskName).dependsOn(project.getTasks().getByName(remapJarTaskName));
+			}
+		}
+
+		try {
+			AbstractArchiveTask sourcesTask = (AbstractArchiveTask) project.getTasks().getByName(sourcesJarTaskName);
+
+			RemapSourcesJarTask remapSourcesJarTask = (RemapSourcesJarTask) project.getTasks().findByName(remapSourcesJarTaskName);
+			Preconditions.checkNotNull(remapSourcesJarTask, "Could not find " + remapSourcesJarTaskName + " in " + project.getName());
+			remapSourcesJarTask.setInput(sourcesTask.getArchivePath());
+			remapSourcesJarTask.setOutput(sourcesTask.getArchivePath());
+			remapSourcesJarTask.dependsOn(project.getTasks().getByName(sourcesJarTaskName));
+
+			if (isDefaultRemap) {
+				remapSourcesJarTask.doLast(task -> project.getArtifacts().add("archives", remapSourcesJarTask.getOutput()));
+			}
+
+			if (extension.isShareCaches()) {
+				remapSourcesJarTask.setSourceRemapper(remapper);
+			}
+
+			parentTask.dependsOn(remapSourcesJarTask);
+		} catch (UnknownTaskException ignored) {
+			// pass
+		}
+	}
+}
diff --git a/src/main/java/net/fabricmc/loom/configuration/ide/RunConfig.java b/src/main/java/net/fabricmc/loom/configuration/ide/RunConfig.java
index 8bbca4fa..603de2db 100644
--- a/src/main/java/net/fabricmc/loom/configuration/ide/RunConfig.java
+++ b/src/main/java/net/fabricmc/loom/configuration/ide/RunConfig.java
@@ -69,6 +69,7 @@ public class RunConfig {
 	public String programArgs;
 	public List<String> vscodeBeforeRun = new ArrayList<>();
 	public final Map<String, String> envVariables = new HashMap<>();
+	public SourceSet sourceSet;
 
 	public Element genRuns(Element doc) {
 		Element root = this.addXml(doc, "component", ImmutableMap.of("name", "ProjectRunConfigurationManager"));
@@ -235,6 +236,7 @@ public class RunConfig {
 		runConfig.ideaModuleName = getIdeaModuleName(project, sourceSet);
 		runConfig.runDirIdeaUrl = "file://$PROJECT_DIR$/" + runDir;
 		runConfig.runDir = runDir;
+		runConfig.sourceSet = sourceSet;
 
 		// Custom parameters
 		for (String progArg : settings.getProgramArgs()) {
diff --git a/src/main/java/net/fabricmc/loom/configuration/providers/MinecraftProvider.java b/src/main/java/net/fabricmc/loom/configuration/providers/MinecraftProvider.java
index b2cb1f49..226f3f17 100644
--- a/src/main/java/net/fabricmc/loom/configuration/providers/MinecraftProvider.java
+++ b/src/main/java/net/fabricmc/loom/configuration/providers/MinecraftProvider.java
@@ -110,7 +110,8 @@ public class MinecraftProvider extends DependencyProvider {
 			try {
 				mergeJars(getProject().getLogger());
 			} catch (ZipError e) {
-				deleteFiles();
+				HashedDownloadUtil.delete(minecraftClientJar);
+				HashedDownloadUtil.delete(minecraftServerJar);
 
 				getProject().getLogger().error("Could not merge JARs! Deleting source JARs - please re-run the command and move on.", e);
 				throw new RuntimeException();
diff --git a/src/main/java/net/fabricmc/loom/configuration/providers/mappings/MappingsProvider.java b/src/main/java/net/fabricmc/loom/configuration/providers/mappings/MappingsProvider.java
index df5aa108..40ae05d0 100644
--- a/src/main/java/net/fabricmc/loom/configuration/providers/mappings/MappingsProvider.java
+++ b/src/main/java/net/fabricmc/loom/configuration/providers/mappings/MappingsProvider.java
@@ -28,6 +28,7 @@ import java.io.BufferedReader;
 import java.io.File;
 import java.io.IOException;
 import java.net.URL;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.FileSystem;
 import java.nio.file.FileSystems;
 import java.nio.file.Files;
@@ -41,6 +42,7 @@ import java.util.function.Consumer;
 
 import com.google.common.base.Preconditions;
 import com.google.common.net.UrlEscapers;
+import com.google.gson.JsonObject;
 import org.apache.commons.io.FileUtils;
 import org.apache.tools.ant.util.StringUtils;
 import org.gradle.api.Project;
@@ -50,6 +52,7 @@ import org.zeroturnaround.zip.ZipEntrySource;
 import org.zeroturnaround.zip.ZipUtil;
 
 import net.fabricmc.loom.LoomGradleExtension;
+import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.configuration.DependencyProvider;
 import net.fabricmc.loom.configuration.accesswidener.AccessWidenerJarProcessor;
 import net.fabricmc.loom.configuration.processors.JarProcessorManager;
@@ -95,6 +98,10 @@ public class MappingsProvider extends DependencyProvider {
 	public File mixinTinyMappingsWithSrg; // FORGE: The mixin mappings have srg names in intermediary.
 	public File srgToNamedSrg; // FORGE: srg to named in srg file format
 
+	private File unpickDefinitionsFile;
+	private boolean hasUnpickDefinitions;
+	private UnpickMetadata unpickMetadata;
+
 	public MappingsProvider(Project project) {
 		super(project);
 		mappingsDir = getExtension().getUserCache().toPath().resolve("mappings");
@@ -173,6 +180,7 @@ public class MappingsProvider extends DependencyProvider {
 		}
 
 		tinyMappings = mappingsDir.resolve(StringUtils.removeSuffix(mappingsJar.getName(), ".jar") + ".tiny").toFile();
+		unpickDefinitionsFile = mappingsDir.resolve(StringUtils.removeSuffix(mappingsJar.getName(), ".jar") + ".unpick").toFile();
 		tinyMappingsJar = new File(getExtension().getUserCache(), mappingsJar.getName().replace(".jar", "-" + jarClassifier + ".jar"));
 		tinyMappingsWithSrg = mappingsDir.resolve(StringUtils.removeSuffix(mappingsJar.getName(), ".jar") + "-srg.tiny");
 		mixinTinyMappingsWithSrg = mappingsDir.resolve(StringUtils.removeSuffix(mappingsJar.getName(), ".jar") + "-mixin-srg.tiny").toFile();
@@ -180,12 +188,27 @@ public class MappingsProvider extends DependencyProvider {
 
 		if (!tinyMappings.exists() || isRefreshDeps()) {
 			storeMappings(getProject(), minecraftProvider, mappingsJar.toPath(), postPopulationScheduler);
+		} else {
+			try (FileSystem fileSystem = FileSystems.newFileSystem(mappingsJar.toPath(), (ClassLoader) null)) {
+				extractUnpickDefinitions(fileSystem, unpickDefinitionsFile.toPath());
+			}
 		}
 
 		if (!tinyMappingsJar.exists() || isRefreshDeps()) {
 			ZipUtil.pack(new ZipEntrySource[] {new FileSource("mappings/mappings.tiny", tinyMappings)}, tinyMappingsJar);
 		}
 
+		if (hasUnpickDefinitions()) {
+			String notation = String.format("%s:%s:%s:constants",
+					dependency.getDependency().getGroup(),
+					dependency.getDependency().getName(),
+					dependency.getDependency().getVersion()
+			);
+
+			getProject().getDependencies().add(Constants.Configurations.MAPPING_CONSTANTS, notation);
+			populateUnpickClasspath();
+		}
+
 		if (getExtension().shouldGenerateSrgTiny()) {
 			if (Files.notExists(tinyMappingsWithSrg) || isRefreshDeps()) {
 				SrgMerger.mergeSrg(getExtension().getSrgProvider().getSrg().toPath(), tinyMappings.toPath(), tinyMappingsWithSrg, true);
@@ -248,6 +271,7 @@ public class MappingsProvider extends DependencyProvider {
 
 		try (FileSystem fileSystem = FileSystems.newFileSystem(yarnJar, (ClassLoader) null)) {
 			extractMappings(fileSystem, baseTinyMappings);
+			extractUnpickDefinitions(fileSystem, unpickDefinitionsFile.toPath());
 		}
 
 		if (baseMappingsAreV2()) {
@@ -317,6 +341,40 @@ public class MappingsProvider extends DependencyProvider {
 		Files.copy(jar.getPath("mappings/mappings.tiny"), extractTo, StandardCopyOption.REPLACE_EXISTING);
 	}
 
+	private void extractUnpickDefinitions(FileSystem jar, Path extractTo) throws IOException {
+		Path unpickPath = jar.getPath("extras/definitions.unpick");
+		Path unpickMetadataPath = jar.getPath("extras/unpick.json");
+
+		if (!Files.exists(unpickPath) || !Files.exists(unpickMetadataPath)) {
+			return;
+		}
+
+		Files.copy(unpickPath, extractTo, StandardCopyOption.REPLACE_EXISTING);
+
+		unpickMetadata = parseUnpickMetadata(unpickMetadataPath);
+		hasUnpickDefinitions = true;
+	}
+
+	private UnpickMetadata parseUnpickMetadata(Path input) throws IOException {
+		JsonObject jsonObject = LoomGradlePlugin.GSON.fromJson(new String(Files.readAllBytes(input), StandardCharsets.UTF_8), JsonObject.class);
+
+		if (!jsonObject.has("version") || jsonObject.get("version").getAsInt() != 1) {
+			throw new UnsupportedOperationException("Unsupported unpick version");
+		}
+
+		return new UnpickMetadata(
+				jsonObject.get("unpickGroup").getAsString(),
+				jsonObject.get("unpickVersion").getAsString()
+		);
+	}
+
+	private void populateUnpickClasspath() {
+		String unpickCliName = "unpick-cli";
+		getProject().getDependencies().add(Constants.Configurations.UNPICK_CLASSPATH,
+				String.format("%s:%s:%s", unpickMetadata.unpickGroup, unpickCliName, unpickMetadata.unpickVersion)
+		);
+	}
+
 	private void extractIntermediary(Path intermediaryJar, Path intermediaryTiny) throws IOException {
 		getProject().getLogger().info(":extracting " + intermediaryJar.getFileName());
 
@@ -439,4 +497,22 @@ public class MappingsProvider extends DependencyProvider {
 	public String getMappingsKey() {
 		return mappingsName + "." + minecraftVersion.replace(' ', '_').replace('.', '_').replace('-', '_') + "." + mappingsVersion;
 	}
+
+	public File getUnpickDefinitionsFile() {
+		return unpickDefinitionsFile;
+	}
+
+	public boolean hasUnpickDefinitions() {
+		return hasUnpickDefinitions;
+	}
+
+	public static class UnpickMetadata {
+		public final String unpickGroup;
+		public final String unpickVersion;
+
+		public UnpickMetadata(String unpickGroup, String unpickVersion) {
+			this.unpickGroup = unpickGroup;
+			this.unpickVersion = unpickVersion;
+		}
+	}
 }
diff --git a/src/main/java/net/fabricmc/loom/configuration/providers/mappings/MojangMappingsDependency.java b/src/main/java/net/fabricmc/loom/configuration/providers/mappings/MojangMappingsDependency.java
index af9dcbdb..09010c87 100644
--- a/src/main/java/net/fabricmc/loom/configuration/providers/mappings/MojangMappingsDependency.java
+++ b/src/main/java/net/fabricmc/loom/configuration/providers/mappings/MojangMappingsDependency.java
@@ -66,7 +66,7 @@ import org.zeroturnaround.zip.ZipUtil;
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.configuration.providers.minecraft.MinecraftVersionMeta;
-import net.fabricmc.loom.util.DownloadUtil;
+import net.fabricmc.loom.util.HashedDownloadUtil;
 import net.fabricmc.lorenztiny.TinyMappingsReader;
 import net.fabricmc.mapping.tree.TinyMappingFactory;
 
@@ -178,11 +178,11 @@ public class MojangMappingsDependency extends AbstractModuleDependency implement
 			throw new RuntimeException("Failed to find official mojang mappings for " + getVersion());
 		}
 
-		String clientMappingsUrl = versionInfo.getDownload(MANIFEST_CLIENT_MAPPINGS).getUrl();
-		String serverMappingsUrl = versionInfo.getDownload(MANIFEST_CLIENT_MAPPINGS).getUrl();
+		MinecraftVersionMeta.Download clientMappingsDownload = versionInfo.getDownload(MANIFEST_CLIENT_MAPPINGS);
+		MinecraftVersionMeta.Download serverMappingsDownload = versionInfo.getDownload(MANIFEST_CLIENT_MAPPINGS);
 
-		DownloadUtil.downloadIfChanged(new URL(clientMappingsUrl), clientMappings.toFile(), project.getLogger());
-		DownloadUtil.downloadIfChanged(new URL(serverMappingsUrl), serverMappings.toFile(), project.getLogger());
+		HashedDownloadUtil.downloadIfInvalid(new URL(clientMappingsDownload.getUrl()), clientMappings.toFile(), clientMappingsDownload.getSha1(), project.getLogger(), false);
+		HashedDownloadUtil.downloadIfInvalid(new URL(serverMappingsDownload.getUrl()), serverMappings.toFile(), clientMappingsDownload.getSha1(), project.getLogger(), false);
 
 		MappingSet mappings = MappingSet.create();
 
diff --git a/src/main/java/net/fabricmc/loom/configuration/providers/minecraft/MinecraftMappedProvider.java b/src/main/java/net/fabricmc/loom/configuration/providers/minecraft/MinecraftMappedProvider.java
index 3b2e9391..891054b6 100644
--- a/src/main/java/net/fabricmc/loom/configuration/providers/minecraft/MinecraftMappedProvider.java
+++ b/src/main/java/net/fabricmc/loom/configuration/providers/minecraft/MinecraftMappedProvider.java
@@ -149,6 +149,8 @@ public class MinecraftMappedProvider extends DependencyProvider {
 
 			getProject().getLogger().lifecycle(":remapping minecraft (TinyRemapper, " + fromM + " -> " + toM + ")");
 
+			Files.deleteIfExists(output);
+
 			try (OutputConsumerPath outputConsumer = new OutputConsumerPath.Builder(output).build()) {
 				if (getExtension().isForge()) {
 					outputConsumer.addNonClassFiles(input, NonClassCopyMode.FIX_META_INF, remapper);
@@ -279,6 +281,10 @@ public class MinecraftMappedProvider extends DependencyProvider {
 		return minecraftMappedJar;
 	}
 
+	public File getUnpickedJar() {
+		return new File(getJarDirectory(getExtension().getUserCache(), "mapped"), "minecraft-" + getJarVersionString("unpicked") + ".jar");
+	}
+
 	@Override
 	public String getTargetConfig() {
 		return Constants.Configurations.MINECRAFT_NAMED;
diff --git a/src/main/java/net/fabricmc/loom/decompilers/fernflower/ForkingJavaExec.java b/src/main/java/net/fabricmc/loom/decompilers/fernflower/ForkingJavaExec.java
index e4b61b02..90080d69 100644
--- a/src/main/java/net/fabricmc/loom/decompilers/fernflower/ForkingJavaExec.java
+++ b/src/main/java/net/fabricmc/loom/decompilers/fernflower/ForkingJavaExec.java
@@ -24,6 +24,9 @@
 
 package net.fabricmc.loom.decompilers.fernflower;
 
+import java.net.URL;
+import java.net.URLClassLoader;
+
 import org.gradle.api.Action;
 import org.gradle.api.Project;
 import org.gradle.api.artifacts.ConfigurationContainer;
@@ -40,15 +43,29 @@ import org.gradle.process.JavaExecSpec;
  */
 public class ForkingJavaExec {
 	public static ExecResult javaexec(Project project, Action<? super JavaExecSpec> action) {
-		ConfigurationContainer configurations = project.getBuildscript().getConfigurations();
-		DependencyHandler handler = project.getDependencies();
-		FileCollection classpath = project.getBuildscript().getConfigurations().getByName("classpath")
-						.plus(project.getRootProject().getBuildscript().getConfigurations().getByName("classpath"))
-						.plus(configurations.detachedConfiguration(handler.localGroovy()));
-
 		return project.javaexec(spec -> {
-			spec.classpath(classpath);
+			spec.classpath(getClasspath(project));
 			action.execute(spec);
 		});
 	}
+
+	private static Object getClasspath(Project project) {
+		if (System.getProperty("fabric.loom.test") != null) {
+			return getTestClasspath();
+		}
+
+		return getRuntimeClasspath(project.getRootProject().getPlugins().hasPlugin("fabric-loom") ? project.getRootProject() : project);
+	}
+
+	private static FileCollection getRuntimeClasspath(Project project) {
+		ConfigurationContainer configurations = project.getBuildscript().getConfigurations();
+		DependencyHandler handler = project.getDependencies();
+		return configurations.getByName("classpath")
+				.plus(project.getRootProject().getBuildscript().getConfigurations().getByName("classpath"))
+				.plus(configurations.detachedConfiguration(handler.localGroovy()));
+	}
+
+	private static URL[] getTestClasspath() {
+		return ((URLClassLoader) ForkingJavaExec.class.getClassLoader()).getURLs();
+	}
 }
diff --git a/src/main/java/net/fabricmc/loom/decompilers/fernflower/TinyJavadocProvider.java b/src/main/java/net/fabricmc/loom/decompilers/fernflower/TinyJavadocProvider.java
index 15cf3bf8..07db43f1 100644
--- a/src/main/java/net/fabricmc/loom/decompilers/fernflower/TinyJavadocProvider.java
+++ b/src/main/java/net/fabricmc/loom/decompilers/fernflower/TinyJavadocProvider.java
@@ -36,6 +36,8 @@ import java.util.Map;
 import org.jetbrains.java.decompiler.struct.StructClass;
 import org.jetbrains.java.decompiler.struct.StructField;
 import org.jetbrains.java.decompiler.struct.StructMethod;
+import org.jetbrains.java.decompiler.struct.StructRecordComponent;
+import org.objectweb.asm.Opcodes;
 
 import net.fabricmc.fernflower.api.IFabricJavadocProvider;
 import net.fabricmc.mapping.tree.ClassDef;
@@ -73,11 +75,63 @@ public class TinyJavadocProvider implements IFabricJavadocProvider {
 	@Override
 	public String getClassDoc(StructClass structClass) {
 		ClassDef classDef = classes.get(structClass.qualifiedName);
-		return classDef != null ? classDef.getComment() : null;
+
+		if (classDef == null) {
+			return null;
+		}
+
+		if (!isRecord(structClass)) {
+			return classDef.getComment();
+		}
+
+		/**
+		 * Handle the record component docs here.
+		 *
+		 * Record components are mapped via the field name, thus take the docs from the fields and display them on then class.
+		 */
+		List<String> parts = new ArrayList<>();
+
+		if (classDef.getComment() != null) {
+			parts.add(classDef.getComment());
+		}
+
+		boolean addedParam = false;
+
+		for (StructRecordComponent component : structClass.getRecordComponents()) {
+			// The component will always match the field name and descriptor
+			FieldDef fieldDef = fields.get(new EntryTriple(structClass.qualifiedName, component.getName(), component.getDescriptor()));
+
+			if (fieldDef == null) {
+				continue;
+			}
+
+			String comment = fieldDef.getComment();
+
+			if (comment != null) {
+				if (!addedParam && classDef.getComment() != null) {
+					//Add a blank line before components when the class has a comment
+					parts.add("");
+					addedParam = true;
+				}
+
+				parts.add(String.format("@param %s %s", fieldDef.getName(namespace), comment));
+			}
+		}
+
+		if (parts.isEmpty()) {
+			return null;
+		}
+
+		return String.join("\n", parts);
 	}
 
 	@Override
 	public String getFieldDoc(StructClass structClass, StructField structField) {
+		// None static fields in records are handled in the class javadoc.
+		if (isRecord(structClass) && !isStatic(structField)) {
+			return null;
+		}
+
 		FieldDef fieldDef = fields.get(new EntryTriple(structClass.qualifiedName, structField.getName(), structField.getDescriptor()));
 		return fieldDef != null ? fieldDef.getComment() : null;
 	}
@@ -126,4 +180,12 @@ public class TinyJavadocProvider implements IFabricJavadocProvider {
 			throw new RuntimeException("Failed to read mappings", e);
 		}
 	}
+
+	public static boolean isRecord(StructClass structClass) {
+		return (structClass.getAccessFlags() & Opcodes.ACC_RECORD) != 0;
+	}
+
+	public static boolean isStatic(StructField structField) {
+		return (structField.getAccessFlags() & Opcodes.ACC_STATIC) != 0;
+	}
 }
diff --git a/src/main/java/net/fabricmc/loom/task/AbstractRunTask.java b/src/main/java/net/fabricmc/loom/task/AbstractRunTask.java
index 61c27abb..34f2dac8 100644
--- a/src/main/java/net/fabricmc/loom/task/AbstractRunTask.java
+++ b/src/main/java/net/fabricmc/loom/task/AbstractRunTask.java
@@ -32,31 +32,23 @@ import java.util.List;
 import java.util.function.Function;
 
 import org.gradle.api.Project;
-import org.gradle.api.plugins.JavaPlugin;
 import org.gradle.api.tasks.JavaExec;
 
-import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.configuration.ide.RunConfig;
 
 public abstract class AbstractRunTask extends JavaExec {
-	private final Function<Project, RunConfig> configProvider;
-	private RunConfig config;
+	private final RunConfig config;
 
-	public AbstractRunTask(Function<Project, RunConfig> config) {
+	public AbstractRunTask(Function<Project, RunConfig> configProvider) {
 		super();
 		setGroup("fabric");
-		this.configProvider = config;
+		this.config = configProvider.apply(getProject());
 
-		setClasspath(getProject().getConfigurations().getByName(JavaPlugin.RUNTIME_CLASSPATH_CONFIGURATION_NAME));
-		classpath(this.getProject().getExtensions().getByType(LoomGradleExtension.class).getUnmappedModCollection());
+		setClasspath(config.sourceSet.getRuntimeClasspath());
 	}
 
 	@Override
 	public void exec() {
-		if (config == null) {
-			config = configProvider.apply(getProject());
-		}
-
 		List<String> argsSplit = new ArrayList<>();
 		String[] args = config.programArgs.split(" ");
 		int partPos = -1;
@@ -94,10 +86,6 @@ public abstract class AbstractRunTask extends JavaExec {
 
 	@Override
 	public void setWorkingDir(File dir) {
-		if (config == null) {
-			config = configProvider.apply(getProject());
-		}
-
 		if (!dir.exists()) {
 			dir.mkdirs();
 		}
@@ -107,19 +95,11 @@ public abstract class AbstractRunTask extends JavaExec {
 
 	@Override
 	public String getMain() {
-		if (config == null) {
-			config = configProvider.apply(getProject());
-		}
-
 		return config.mainClass;
 	}
 
 	@Override
 	public List<String> getJvmArgs() {
-		if (config == null) {
-			config = configProvider.apply(getProject());
-		}
-
 		List<String> superArgs = super.getJvmArgs();
 		List<String> args = new ArrayList<>(superArgs != null ? superArgs : Collections.emptyList());
 		args.addAll(Arrays.asList(config.vmArgs.split(" ")));
diff --git a/src/main/java/net/fabricmc/loom/task/GenerateSourcesTask.java b/src/main/java/net/fabricmc/loom/task/GenerateSourcesTask.java
index 7c5862e4..25d6fe47 100644
--- a/src/main/java/net/fabricmc/loom/task/GenerateSourcesTask.java
+++ b/src/main/java/net/fabricmc/loom/task/GenerateSourcesTask.java
@@ -35,6 +35,7 @@ import java.util.stream.Collectors;
 
 import javax.inject.Inject;
 
+import org.gradle.api.tasks.InputFile;
 import org.gradle.api.tasks.TaskAction;
 
 import net.fabricmc.loom.LoomGradleExtension;
@@ -49,6 +50,8 @@ import net.fabricmc.stitch.util.StitchUtil;
 public class GenerateSourcesTask extends AbstractLoomTask {
 	public final LoomDecompiler decompiler;
 
+	private File inputJar;
+
 	@Inject
 	public GenerateSourcesTask(LoomDecompiler decompiler) {
 		this.decompiler = decompiler;
@@ -65,26 +68,18 @@ public class GenerateSourcesTask extends AbstractLoomTask {
 						.stream().map(File::toPath).collect(Collectors.toSet());
 
 		DecompilationMetadata metadata = new DecompilationMetadata(threads, javaDocs, libraries);
-		Path compiledJar = getExtension().getMappingsProvider().mappedProvider.getMappedJar().toPath();
+		Path runtimeJar = getExtension().getMappingsProvider().mappedProvider.getMappedJar().toPath();
 		Path sourcesDestination = getMappedJarFileWithSuffix("-sources.jar").toPath();
 		Path linemap = getMappedJarFileWithSuffix("-sources.lmap").toPath();
-		decompiler.decompile(compiledJar, sourcesDestination, linemap, metadata);
+		decompiler.decompile(inputJar.toPath(), sourcesDestination, linemap, metadata);
 
 		if (Files.exists(linemap)) {
 			Path linemappedJarDestination = getMappedJarFileWithSuffix("-linemapped.jar").toPath();
 
-			remapLineNumbers(compiledJar, linemap, linemappedJarDestination);
-
-			// In order for IDEs to recognize the new line mappings, we need to overwrite the existing compiled jar
-			// with the linemapped one. In the name of not destroying the existing jar, we will copy it to somewhere else.
-			Path unlinemappedJar = getMappedJarFileWithSuffix("-unlinemapped.jar").toPath();
+			// Line map the actually jar used to run the game, not the one used to decompile
+			remapLineNumbers(runtimeJar, linemap, linemappedJarDestination);
 
-			// The second time genSources is ran, we want to keep the existing unlinemapped jar.
-			if (!Files.exists(unlinemappedJar)) {
-				Files.copy(compiledJar, unlinemappedJar);
-			}
-
-			Files.copy(linemappedJarDestination, compiledJar, StandardCopyOption.REPLACE_EXISTING);
+			Files.copy(linemappedJarDestination, runtimeJar, StandardCopyOption.REPLACE_EXISTING);
 			Files.delete(linemappedJarDestination);
 		}
 	}
@@ -117,4 +112,14 @@ public class GenerateSourcesTask extends AbstractLoomTask {
 
 		return new File(path.substring(0, path.length() - 4) + suffix);
 	}
+
+	@InputFile
+	public File getInputJar() {
+		return inputJar;
+	}
+
+	public GenerateSourcesTask setInputJar(File inputJar) {
+		this.inputJar = inputJar;
+		return this;
+	}
 }
diff --git a/src/main/java/net/fabricmc/loom/task/LoomTasks.java b/src/main/java/net/fabricmc/loom/task/LoomTasks.java
index 198f92e6..1b1de6a7 100644
--- a/src/main/java/net/fabricmc/loom/task/LoomTasks.java
+++ b/src/main/java/net/fabricmc/loom/task/LoomTasks.java
@@ -24,6 +24,8 @@
 
 package net.fabricmc.loom.task;
 
+import java.io.File;
+
 import com.google.common.base.Preconditions;
 import org.gradle.api.Project;
 import org.gradle.api.tasks.TaskContainer;
@@ -31,6 +33,7 @@ import org.gradle.api.tasks.TaskContainer;
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.api.decompilers.LoomDecompiler;
 import net.fabricmc.loom.configuration.ide.RunConfigSettings;
+import net.fabricmc.loom.configuration.providers.mappings.MappingsProvider;
 import net.fabricmc.loom.decompilers.fernflower.FabricFernFlowerDecompiler;
 
 public final class LoomTasks {
@@ -110,10 +113,30 @@ public final class LoomTasks {
 		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
 
 		project.afterEvaluate(p -> {
+			MappingsProvider mappingsProvider = extension.getMappingsProvider();
+			File inputJar = mappingsProvider.mappedProvider.getMappedJar();
+
+			if (mappingsProvider.hasUnpickDefinitions()) {
+				File outputJar = mappingsProvider.mappedProvider.getUnpickedJar();
+
+				tasks.register("unpickJar", UnpickJarTask.class, unpickJarTask -> {
+					unpickJarTask.setUnpickDefinition(mappingsProvider.getUnpickDefinitionsFile());
+					unpickJarTask.setInputJar(mappingsProvider.mappedProvider.getMappedJar());
+					unpickJarTask.setOutputJar(outputJar);
+				});
+
+				inputJar = outputJar;
+			}
+
 			for (LoomDecompiler decompiler : extension.getDecompilers()) {
 				String taskName = decompiler instanceof FabricFernFlowerDecompiler ? "genSources" : "genSourcesWith" + decompiler.name();
 				// decompiler will be passed to the constructor of GenerateSourcesTask
-				tasks.register(taskName, GenerateSourcesTask.class, decompiler);
+				GenerateSourcesTask generateSourcesTask = tasks.register(taskName, GenerateSourcesTask.class, decompiler).get();
+				generateSourcesTask.setInputJar(inputJar);
+
+				if (mappingsProvider.hasUnpickDefinitions()) {
+					generateSourcesTask.dependsOn(tasks.getByName("unpickJar"));
+				}
 			}
 		});
 	}
diff --git a/src/main/java/net/fabricmc/loom/task/RemapJarTask.java b/src/main/java/net/fabricmc/loom/task/RemapJarTask.java
index 25165098..7b3c923e 100644
--- a/src/main/java/net/fabricmc/loom/task/RemapJarTask.java
+++ b/src/main/java/net/fabricmc/loom/task/RemapJarTask.java
@@ -36,7 +36,10 @@ import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.AbstractMap;
 import java.util.ArrayList;
+import java.util.Collections;
+import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.Set;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
@@ -53,6 +56,7 @@ import me.shedaniel.architectury.refmapremapper.remapper.Remapper;
 import me.shedaniel.architectury.refmapremapper.remapper.SimpleReferenceRemapper;
 import org.gradle.api.Action;
 import org.gradle.api.Project;
+import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.file.FileCollection;
 import org.gradle.api.file.RegularFileProperty;
 import org.gradle.api.provider.Property;
@@ -60,19 +64,25 @@ import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.InputFile;
 import org.gradle.api.tasks.TaskAction;
 import org.gradle.jvm.tasks.Jar;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.Nullable;
 import org.zeroturnaround.zip.ZipUtil;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.build.JarRemapper;
 import net.fabricmc.loom.build.MixinRefmapHelper;
-import net.fabricmc.loom.build.NestedJars;
+import net.fabricmc.loom.build.nesting.NestedJarPathProvider;
+import net.fabricmc.loom.build.nesting.JarNester;
+import net.fabricmc.loom.build.nesting.MergedNestedJarProvider;
+import net.fabricmc.loom.build.nesting.NestedDependencyProvider;
+import net.fabricmc.loom.build.nesting.NestedJarProvider;
 import net.fabricmc.loom.configuration.accesswidener.AccessWidenerJarProcessor;
 import net.fabricmc.loom.configuration.providers.mappings.MappingsProvider;
+import net.fabricmc.loom.util.Constants;
 import net.fabricmc.loom.util.LoggerFilter;
 import net.fabricmc.loom.util.TinyRemapperMappingsHelper;
-import net.fabricmc.loom.util.ZipReprocessorUtil;
 import net.fabricmc.loom.util.gradle.GradleSupport;
+import net.fabricmc.loom.util.ZipReprocessorUtil;
 import net.fabricmc.mapping.tree.ClassDef;
 import net.fabricmc.mapping.tree.FieldDef;
 import net.fabricmc.mapping.tree.MethodDef;
@@ -86,17 +96,20 @@ import net.fabricmc.tinyremapper.TinyUtils;
 public class RemapJarTask extends Jar {
 	private final RegularFileProperty input;
 	private final Property<Boolean> addNestedDependencies;
+	private final Property<Boolean> addDefaultNestedDependencies;
 	private final Property<Boolean> remapAccessWidener;
 	private final List<Action<TinyRemapper.Builder>> remapOptions = new ArrayList<>();
 	private final Property<String> fromM;
 	private final Property<String> toM;
 	public JarRemapper jarRemapper;
 	private FileCollection classpath;
+	private final Set<Object> nestedPaths = new LinkedHashSet<>();
 
 	public RemapJarTask() {
 		super();
 		input = GradleSupport.getfileProperty(getProject());
 		addNestedDependencies = getProject().getObjects().property(Boolean.class);
+		addDefaultNestedDependencies = getProject().getObjects().property(Boolean.class);
 		remapAccessWidener = getProject().getObjects().property(Boolean.class);
 		fromM = getProject().getObjects().property(String.class);
 		toM = getProject().getObjects().property(String.class);
@@ -104,199 +117,26 @@ public class RemapJarTask extends Jar {
 		toM.set("intermediary");
 		// false by default, I have no idea why I have to do it for this property and not the other one
 		remapAccessWidener.set(false);
+		addDefaultNestedDependencies.set(true);
 	}
 
 	@TaskAction
 	public void doTask() throws Throwable {
-		if (jarRemapper == null) {
-			doSingleRemap();
-		} else {
-			scheduleRemap();
-		}
-	}
-
-	public void doSingleRemap() throws Throwable {
-		Project project = getProject();
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
-		Path input = this.getInput().getAsFile().get().toPath();
-		Path output = this.getArchivePath().toPath();
-
-		if (!Files.exists(input)) {
-			throw new FileNotFoundException(input.toString());
-		}
-
-		MappingsProvider mappingsProvider = extension.getMappingsProvider();
-
-		String fromM = this.fromM.get();
-		String toM = this.toM.get();
-
-		Path[] classpath = getRemapClasspath();
-
-		LoggerFilter.replaceSystemOut();
-		TinyRemapper.Builder remapperBuilder = TinyRemapper.newRemapper();
-		remapperBuilder.logger(getProject().getLogger()::lifecycle);
-		remapperBuilder = remapperBuilder.withMappings(TinyRemapperMappingsHelper.create(extension.isForge() ? mappingsProvider.getMappingsWithSrg() : mappingsProvider.getMappings(), fromM, toM, false));
-
-		for (File mixinMapFile : extension.getAllMixinMappings()) {
-			if (mixinMapFile.exists()) {
-				IMappingProvider provider = TinyUtils.createTinyMappingProvider(mixinMapFile.toPath(), fromM, "intermediary");
-				remapperBuilder = remapperBuilder.withMappings(extension.isForge() ? remapToSrg(extension, provider) : provider);
-			}
-		}
-
-		// Apply any requested options to tiny remapper
-		for (Action<TinyRemapper.Builder> remapOption : this.remapOptions) {
-			remapOption.execute(remapperBuilder);
-		}
-
-		project.getLogger().info(":remapping " + input.getFileName());
-
-		StringBuilder rc = new StringBuilder("Remap classpath: ");
-
-		for (Path p : classpath) {
-			rc.append("\n - ").append(p.toString());
-		}
-
-		project.getLogger().debug(rc.toString());
-
-		TinyRemapper remapper = remapperBuilder.build();
-
-		try (OutputConsumerPath outputConsumer = new OutputConsumerPath.Builder(output).build()) {
-			outputConsumer.addNonClassFiles(input);
-			remapper.readClassPath(classpath);
-			remapper.readInputs(input);
-			remapper.apply(outputConsumer);
-		} catch (Exception e) {
-			remapper.finish();
-			throw new RuntimeException("Failed to remap " + input + " to " + output, e);
-		}
-
-		if (getRemapAccessWidener().getOrElse(false) && extension.accessWidener != null) {
-			extension.getJarProcessorManager().getByType(AccessWidenerJarProcessor.class).remapAccessWidener(output, remapper.getRemapper());
-		}
-
-		remapper.finish();
-
-		if (!Files.exists(output)) {
-			throw new RuntimeException("Failed to remap " + input + " to " + output + " - file missing!");
-		}
-
-		if (MixinRefmapHelper.addRefmapName(extension.getRefmapName(), output)) {
-			project.getLogger().debug("Transformed mixin reference maps in output JAR!");
-		}
+		boolean singleRemap = false;
 
-		if (extension.isForge()) {
-			try (FileSystem fs = FileSystems.newFileSystem(URI.create("jar:" + output.toUri()), ImmutableMap.of("create", false))) {
-				Path refmapPath = fs.getPath(extension.getRefmapName());
-
-				if (Files.exists(refmapPath)) {
-					try (Reader refmapReader = Files.newBufferedReader(refmapPath, StandardCharsets.UTF_8)) {
-						Gson gson = new GsonBuilder().disableHtmlEscaping().setPrettyPrinting().create();
-						JsonObject refmapElement = gson.fromJson(refmapReader, JsonObject.class);
-						refmapElement = RefmapRemapper.remap(new Remapper() {
-							ReferenceRemapper remapper = createReferenceRemapper(extension);
-
-							@Override
-							@Nullable
-							public MappingsRemapper remapMappings() {
-								return className -> remapper;
-							}
-
-							@Override
-							@Nullable
-							public Map.Entry<String, @Nullable MappingsRemapper> remapMappingsData(String data) {
-								if (Objects.equals(data, "named:intermediary")) {
-									return new AbstractMap.SimpleEntry<>("searge", remapMappings());
-								}
-
-								return null;
-							}
-						}, refmapElement);
-						Files.delete(refmapPath);
-						Files.write(refmapPath, gson.toJson(refmapElement).getBytes(StandardCharsets.UTF_8));
-					}
-				}
-			}
+		if (jarRemapper == null) {
+			singleRemap = true;
+			jarRemapper = new JarRemapper();
 		}
 
-		if (getAddNestedDependencies().getOrElse(false)) {
-			if (NestedJars.addNestedJars(project, output)) {
-				project.getLogger().debug("Added nested jar paths to mod json");
-			}
-		}
+		scheduleRemap(singleRemap || getProject().getExtensions().getByType(LoomGradleExtension.class).isRootProject());
 
-		if (isReproducibleFileOrder() || isPreserveFileTimestamps()) {
-			ZipReprocessorUtil.reprocessZip(output.toFile(), isReproducibleFileOrder(), isPreserveFileTimestamps());
+		if (singleRemap) {
+			jarRemapper.remap();
 		}
 	}
 
-	private ReferenceRemapper createReferenceRemapper(LoomGradleExtension extension) throws IOException {
-		TinyTree srg = extension.getMappingsProvider().getMappingsWithSrg();
-
-		return new SimpleReferenceRemapper(new SimpleReferenceRemapper.Remapper() {
-			@Override
-			@Nullable
-			public String mapClass(String value) {
-				return srg.getClasses().stream()
-						.filter(classDef -> Objects.equals(classDef.getName("intermediary"), value))
-						.findFirst()
-						.map(classDef -> classDef.getName("srg"))
-						.orElse(null);
-			}
-
-			@Override
-			@Nullable
-			public String mapMethod(@Nullable String className, String methodName, String methodDescriptor) {
-				if (className != null) {
-					Optional<ClassDef> classDef = srg.getClasses().stream()
-							.filter(c -> Objects.equals(c.getName("intermediary"), className))
-							.findFirst();
-
-					if (classDef.isPresent()) {
-						for (MethodDef methodDef : classDef.get().getMethods()) {
-							if (Objects.equals(methodDef.getName("intermediary"), methodName) && Objects.equals(methodDef.getDescriptor("intermediary"), methodDescriptor)) {
-								return methodDef.getName("srg");
-							}
-						}
-					}
-				}
-
-				return srg.getClasses().stream()
-						.flatMap(classDef -> classDef.getMethods().stream())
-						.filter(methodDef -> Objects.equals(methodDef.getName("intermediary"), methodName) && Objects.equals(methodDef.getDescriptor("intermediary"), methodDescriptor))
-						.findFirst()
-						.map(methodDef -> methodDef.getName("srg"))
-						.orElse(null);
-			}
-
-			@Override
-			@Nullable
-			public String mapField(@Nullable String className, String fieldName, String fieldDescriptor) {
-				if (className != null) {
-					Optional<ClassDef> classDef = srg.getClasses().stream()
-							.filter(c -> Objects.equals(c.getName("intermediary"), className))
-							.findFirst();
-
-					if (classDef.isPresent()) {
-						for (FieldDef fieldDef : classDef.get().getFields()) {
-							if (Objects.equals(fieldDef.getName("intermediary"), fieldName) && Objects.equals(fieldDef.getDescriptor("intermediary"), fieldDescriptor)) {
-								return fieldDef.getName("srg");
-							}
-						}
-					}
-				}
-
-				return srg.getClasses().stream()
-						.flatMap(classDef -> classDef.getFields().stream())
-						.filter(fieldDef -> Objects.equals(fieldDef.getName("intermediary"), fieldName) && Objects.equals(fieldDef.getDescriptor("intermediary"), fieldDescriptor))
-						.findFirst()
-						.map(fieldDef -> fieldDef.getName("srg"))
-						.orElse(null);
-			}
-		});
-	}
-
-	public void scheduleRemap() throws Throwable {
+	public void scheduleRemap(boolean isMainRemapTask) throws Throwable {
 		Project project = getProject();
 		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
 		Path input = this.getInput().getAsFile().get().toPath();
@@ -311,7 +151,7 @@ public class RemapJarTask extends Jar {
 		String fromM = this.fromM.get();
 		String toM = this.toM.get();
 
-		if (extension.isRootProject()) {
+		if (isMainRemapTask) {
 			jarRemapper.addToClasspath(getRemapClasspath());
 
 			jarRemapper.addMappings(TinyRemapperMappingsHelper.create(extension.isForge() ? mappingsProvider.getMappingsWithSrg() : mappingsProvider.getMappings(), fromM, toM, false));
@@ -327,6 +167,9 @@ public class RemapJarTask extends Jar {
 		// Add remap options to the jar remapper
 		jarRemapper.addOptions(this.remapOptions);
 
+		NestedJarProvider nestedJarProvider = getNestedJarProvider();
+		nestedJarProvider.prepare(getProject());
+
 		jarRemapper.scheduleRemap(input, output)
 				.supplyAccessWidener((remapData, remapper) -> {
 					if (getRemapAccessWidener().getOrElse(false) && extension.accessWidener != null) {
@@ -357,18 +200,43 @@ public class RemapJarTask extends Jar {
 					}
 
 					if (getAddNestedDependencies().getOrElse(false)) {
-						if (NestedJars.addNestedJars(project, output)) {
-							project.getLogger().debug("Added nested jar paths to mod json");
-						}
+						JarNester.nestJars(nestedJarProvider.provide(), output.toFile(), project.getLogger());
 					}
 
 					if (accessWidener != null) {
 						boolean replaced = ZipUtil.replaceEntry(data.output.toFile(), accessWidener.getLeft(), accessWidener.getRight());
 						Preconditions.checkArgument(replaced, "Failed to remap access widener");
 					}
+
+					if (isReproducibleFileOrder() || !isPreserveFileTimestamps()) {
+						try {
+							ZipReprocessorUtil.reprocessZip(output.toFile(), isReproducibleFileOrder(), isPreserveFileTimestamps());
+						} catch (IOException e) {
+							throw new RuntimeException("Failed to re-process jar", e);
+						}
+					}
 				});
 	}
 
+	private NestedJarProvider getNestedJarProvider() {
+		Configuration includeConfiguration = getProject().getConfigurations().getByName(Constants.Configurations.INCLUDE);
+
+		if (!addDefaultNestedDependencies.getOrElse(true)) {
+			return new NestedJarPathProvider(nestedPaths);
+		}
+
+		NestedJarProvider baseProvider = NestedDependencyProvider.createNestedDependencyProviderFromConfiguration(getProject(), includeConfiguration);
+
+		if (nestedPaths.isEmpty()) {
+			return baseProvider;
+		}
+
+		return new MergedNestedJarProvider(
+				baseProvider,
+				new NestedJarPathProvider(nestedPaths)
+		);
+	}
+
 	private IMappingProvider remapToSrg(LoomGradleExtension extension, IMappingProvider parent) throws IOException {
 		TinyTree srg = extension.getMappingsProvider().getMappingsWithSrg();
 
@@ -444,6 +312,11 @@ public class RemapJarTask extends Jar {
 	}
 
 	@Input
+	public Property<Boolean> getAddDefaultNestedDependencies() {
+		return addDefaultNestedDependencies;
+	}
+
+	@Input
 	public Property<Boolean> getRemapAccessWidener() {
 		return remapAccessWidener;
 	}
@@ -462,6 +335,14 @@ public class RemapJarTask extends Jar {
 		return this;
 	}
 
+	@ApiStatus.Experimental // This only allows mod jars, proceed with care when trying to pass in configurations with projects, or something that depends on a task.
+	public RemapJarTask include(Object... paths) {
+		Collections.addAll(nestedPaths, paths);
+		this.addNestedDependencies.set(true);
+
+		return this;
+	}
+
 	@Input
 	public Property<String> getFromM() {
 		return fromM;
diff --git a/src/main/java/net/fabricmc/loom/task/RemapSourcesJarTask.java b/src/main/java/net/fabricmc/loom/task/RemapSourcesJarTask.java
index 2d388fba..9548ad7f 100644
--- a/src/main/java/net/fabricmc/loom/task/RemapSourcesJarTask.java
+++ b/src/main/java/net/fabricmc/loom/task/RemapSourcesJarTask.java
@@ -26,8 +26,6 @@ package net.fabricmc.loom.task;
 
 import java.io.File;
 
-import org.gradle.api.model.ObjectFactory;
-import org.gradle.api.provider.Property;
 import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.InputFile;
 import org.gradle.api.tasks.Internal;
@@ -35,29 +33,24 @@ import org.gradle.api.tasks.OutputFile;
 import org.gradle.api.tasks.TaskAction;
 
 import net.fabricmc.loom.util.SourceRemapper;
-import net.fabricmc.loom.util.ZipReprocessorUtil;
 
 public class RemapSourcesJarTask extends AbstractLoomTask {
 	private Object input;
 	private Object output;
 	private String direction = "intermediary";
 	private SourceRemapper sourceRemapper = null;
-	private final Property<Boolean> archivePreserveFileTimestamps;
-	private final Property<Boolean> archiveReproducibleFileOrder;
+	private boolean preserveFileTimestamps = true;
+	private boolean reproducibleFileOrder = false;
 
 	public RemapSourcesJarTask() {
-		ObjectFactory objectFactory = getProject().getObjects();
-		archivePreserveFileTimestamps = objectFactory.property(Boolean.class);
-		archiveReproducibleFileOrder = objectFactory.property(Boolean.class);
 	}
 
 	@TaskAction
 	public void remap() throws Exception {
 		if (sourceRemapper == null) {
-			SourceRemapper.remapSources(getProject(), getInput(), getOutput(), direction.equals("named"));
-			ZipReprocessorUtil.reprocessZip(getOutput(), archivePreserveFileTimestamps.getOrElse(true), archiveReproducibleFileOrder.getOrElse(false));
+			SourceRemapper.remapSources(getProject(), getInput(), getOutput(), direction.equals("named"), reproducibleFileOrder, preserveFileTimestamps);
 		} else {
-			sourceRemapper.scheduleRemapSources(getInput(), getOutput(), archivePreserveFileTimestamps.getOrElse(true), archiveReproducibleFileOrder.getOrElse(false));
+			sourceRemapper.scheduleRemapSources(getInput(), getOutput(), reproducibleFileOrder, preserveFileTimestamps);
 		}
 	}
 
@@ -97,4 +90,22 @@ public class RemapSourcesJarTask extends AbstractLoomTask {
 	public void setTargetNamespace(String value) {
 		this.direction = value;
 	}
+
+	@Input
+	public boolean isPreserveFileTimestamps() {
+		return preserveFileTimestamps;
+	}
+
+	public void setPreserveFileTimestamps(boolean preserveFileTimestamps) {
+		this.preserveFileTimestamps = preserveFileTimestamps;
+	}
+
+	@Input
+	public boolean isReproducibleFileOrder() {
+		return reproducibleFileOrder;
+	}
+
+	public void setReproducibleFileOrder(boolean reproducibleFileOrder) {
+		this.reproducibleFileOrder = reproducibleFileOrder;
+	}
 }
diff --git a/src/main/java/net/fabricmc/loom/task/UnpickJarTask.java b/src/main/java/net/fabricmc/loom/task/UnpickJarTask.java
new file mode 100644
index 00000000..e27d2ff2
--- /dev/null
+++ b/src/main/java/net/fabricmc/loom/task/UnpickJarTask.java
@@ -0,0 +1,126 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.task;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+
+import org.gradle.api.tasks.InputFile;
+import org.gradle.api.tasks.Internal;
+import org.gradle.api.tasks.JavaExec;
+import org.gradle.api.tasks.OutputFile;
+
+import net.fabricmc.loom.LoomGradleExtension;
+import net.fabricmc.loom.configuration.providers.LaunchProvider;
+import net.fabricmc.loom.util.Constants;
+
+public class UnpickJarTask extends JavaExec {
+	File inputJar;
+	File unpickDefinition;
+
+	File outputJar;
+
+	public UnpickJarTask() {
+		getOutputs().upToDateWhen(e -> false);
+		classpath(getProject().getConfigurations().getByName(Constants.Configurations.UNPICK_CLASSPATH));
+		setMain("daomephsta.unpick.cli.Main");
+	}
+
+	@Override
+	public void exec() {
+		fileArg(getInputJar(), getOutputJar(), getUnpickDefinition());
+		fileArg(getConstantJar());
+
+		// Classpath
+		fileArg(getExtension().getMinecraftMappedProvider().getMappedJar());
+		fileArg(getMinecraftDependencies());
+
+		writeUnpickLogConfig();
+		systemProperty("java.util.logging.config.file", getExtension().getUnpickLoggingConfigFile().getAbsolutePath());
+
+		super.exec();
+	}
+
+	private void writeUnpickLogConfig() {
+		try (InputStream is = LaunchProvider.class.getClassLoader().getResourceAsStream("unpick-logging.properties")) {
+			Files.deleteIfExists(getExtension().getUnpickLoggingConfigFile().toPath());
+			Files.copy(is, getExtension().getUnpickLoggingConfigFile().toPath());
+		} catch (IOException e) {
+			throw new RuntimeException("Failed to copy unpick logging config", e);
+		}
+	}
+
+	private File[] getMinecraftDependencies() {
+		return getProject().getConfigurations().getByName(Constants.Configurations.MINECRAFT_DEPENDENCIES)
+				.resolve().toArray(new File[0]);
+	}
+
+	private File getConstantJar() {
+		return getProject().getConfigurations().getByName(Constants.Configurations.MAPPING_CONSTANTS).getSingleFile();
+	}
+
+	@InputFile
+	public File getInputJar() {
+		return inputJar;
+	}
+
+	public UnpickJarTask setInputJar(File inputJar) {
+		this.inputJar = inputJar;
+		return this;
+	}
+
+	@InputFile
+	public File getUnpickDefinition() {
+		return unpickDefinition;
+	}
+
+	public UnpickJarTask setUnpickDefinition(File unpickDefinition) {
+		this.unpickDefinition = unpickDefinition;
+		return this;
+	}
+
+	@OutputFile
+	public File getOutputJar() {
+		return outputJar;
+	}
+
+	public UnpickJarTask setOutputJar(File outputJar) {
+		this.outputJar = outputJar;
+		return this;
+	}
+
+	private void fileArg(File... files) {
+		for (File file : files) {
+			args(file.getAbsolutePath());
+		}
+	}
+
+	@Internal
+	protected LoomGradleExtension getExtension() {
+		return getProject().getExtensions().getByType(LoomGradleExtension.class);
+	}
+}
diff --git a/src/main/java/net/fabricmc/loom/util/Constants.java b/src/main/java/net/fabricmc/loom/util/Constants.java
index 2e124766..b9059217 100644
--- a/src/main/java/net/fabricmc/loom/util/Constants.java
+++ b/src/main/java/net/fabricmc/loom/util/Constants.java
@@ -87,6 +87,8 @@ public class Constants {
 		public static final String FORGE_DEPENDENCIES = "forgeDependencies";
 		@Deprecated // Not to be used in gradle 7+
 		public static final String COMPILE = "compile";
+		public static final String MAPPING_CONSTANTS = "mappingsConstants";
+		public static final String UNPICK_CLASSPATH = "unpick";
 
 		private Configurations() {
 		}
diff --git a/src/main/java/net/fabricmc/loom/util/DownloadUtil.java b/src/main/java/net/fabricmc/loom/util/DownloadUtil.java
index 8d4865a6..1da65ae5 100644
--- a/src/main/java/net/fabricmc/loom/util/DownloadUtil.java
+++ b/src/main/java/net/fabricmc/loom/util/DownloadUtil.java
@@ -89,6 +89,7 @@ public class DownloadUtil {
 
 		if ((code < 200 || code > 299) && code != HttpURLConnection.HTTP_NOT_MODIFIED) {
 			//Didn't get what we expected
+			delete(to);
 			throw new IOException(connection.getResponseMessage() + " for " + from);
 		}
 
@@ -111,7 +112,7 @@ public class DownloadUtil {
 		try { // Try download to the output
 			FileUtils.copyInputStreamToFile(connection.getInputStream(), to);
 		} catch (IOException e) {
-			to.delete(); // Probably isn't good if it fails to copy/save
+			delete(to); // Probably isn't good if it fails to copy/save
 			throw e;
 		}
 
diff --git a/src/main/java/net/fabricmc/loom/util/GroovyXmlUtil.java b/src/main/java/net/fabricmc/loom/util/GroovyXmlUtil.java
index 801cc118..4e587e10 100644
--- a/src/main/java/net/fabricmc/loom/util/GroovyXmlUtil.java
+++ b/src/main/java/net/fabricmc/loom/util/GroovyXmlUtil.java
@@ -31,6 +31,8 @@ import java.util.stream.Stream;
 import groovy.util.Node;
 import groovy.xml.QName;
 
+import net.fabricmc.loom.util.gradle.GradleSupport;
+
 public final class GroovyXmlUtil {
 	private GroovyXmlUtil() { }
 
@@ -63,9 +65,19 @@ public final class GroovyXmlUtil {
 			return ((QName) nodeName).matches(givenName);
 		}
 
+		// New groovy 3 (gradle 7) class
+		if (GradleSupport.IS_GRADLE_7_OR_NEWER && nodeName.getClass().getName().equals("groovy.namespace.QName")) {
+			return isSameNameGroovy3(nodeName, givenName);
+		}
+
 		throw new UnsupportedOperationException("Cannot determine if " + nodeName.getClass() + " is the same as a String");
 	}
 
+	// TODO Move out of its own method when requiring gradle 7
+	private static boolean isSameNameGroovy3(Object nodeName, String givenName) {
+		return ((groovy.namespace.QName) nodeName).matches(givenName);
+	}
+
 	public static Stream<Node> childrenNodesStream(Node node) {
 		//noinspection unchecked
 		return (Stream<Node>) (Stream) (((List<Object>) node.children()).stream().filter((i) -> i instanceof Node));
diff --git a/src/main/java/net/fabricmc/loom/util/HashedDownloadUtil.java b/src/main/java/net/fabricmc/loom/util/HashedDownloadUtil.java
index 4ca156ac..a03126d1 100644
--- a/src/main/java/net/fabricmc/loom/util/HashedDownloadUtil.java
+++ b/src/main/java/net/fabricmc/loom/util/HashedDownloadUtil.java
@@ -25,6 +25,7 @@
 package net.fabricmc.loom.util;
 
 import java.io.File;
+import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.net.HttpURLConnection;
 import java.net.URL;
@@ -60,6 +61,10 @@ public class HashedDownloadUtil {
 	}
 
 	public static void downloadIfInvalid(URL from, File to, String expectedHash, Logger logger, boolean quiet, boolean strict) throws IOException {
+		downloadIfInvalid(from, to, expectedHash, logger, quiet, strict, () -> { });
+	}
+
+	public static void downloadIfInvalid(URL from, File to, String expectedHash, Logger logger, boolean quiet, boolean strict, Runnable startDownload) throws IOException {
 		if (LoomGradlePlugin.refreshDeps) {
 			delete(to);
 		}
@@ -80,6 +85,8 @@ public class HashedDownloadUtil {
 			}
 		}
 
+		startDownload.run();
+
 		HttpURLConnection connection = (HttpURLConnection) from.openConnection();
 		connection.setRequestProperty("Accept-Encoding", "gzip");
 		connection.connect();
@@ -121,14 +128,18 @@ public class HashedDownloadUtil {
 
 	@Nullable
 	private static String getSha1(File to, Logger logger) {
-		File sha1File = getSha1File(to);
-
-		if (!sha1File.exists()) {
+		if (!to.exists()) {
+			delete(to);
 			return null;
 		}
 
+		File sha1File = getSha1File(to);
+
 		try {
 			return Files.asCharSource(sha1File, StandardCharsets.UTF_8).read();
+		} catch (FileNotFoundException ignored) {
+			// Quicker to catch this than do an exists check before.
+			return null;
 		} catch (IOException e) {
 			logger.warn("Error reading sha1 file '{}'.", sha1File);
 			return null;
diff --git a/src/main/java/net/fabricmc/loom/util/ModUtils.java b/src/main/java/net/fabricmc/loom/util/ModUtils.java
new file mode 100644
index 00000000..1dfc43b2
--- /dev/null
+++ b/src/main/java/net/fabricmc/loom/util/ModUtils.java
@@ -0,0 +1,42 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.util;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.zip.ZipFile;
+
+public final class ModUtils {
+	private ModUtils() {
+	}
+
+	public static boolean isMod(File input) {
+		try (ZipFile zipFile = new ZipFile(input)) {
+			return zipFile.getEntry("fabric.mod.json") != null;
+		} catch (IOException e) {
+			return false;
+		}
+	}
+}
diff --git a/src/main/java/net/fabricmc/loom/util/OperatingSystem.java b/src/main/java/net/fabricmc/loom/util/OperatingSystem.java
index 2f69bcb8..db622790 100644
--- a/src/main/java/net/fabricmc/loom/util/OperatingSystem.java
+++ b/src/main/java/net/fabricmc/loom/util/OperatingSystem.java
@@ -49,6 +49,10 @@ public class OperatingSystem {
 		return System.getProperty("sun.arch.data.model").contains("64");
 	}
 
+	public static boolean isWindows() {
+		return getOS().equals("windows");
+	}
+
 	public static boolean isCIBuild() {
 		String loomProperty = System.getProperty("fabric.loom.ci");
 
diff --git a/src/main/java/net/fabricmc/loom/util/SourceRemapper.java b/src/main/java/net/fabricmc/loom/util/SourceRemapper.java
index 0acc4693..dc6c7f58 100644
--- a/src/main/java/net/fabricmc/loom/util/SourceRemapper.java
+++ b/src/main/java/net/fabricmc/loom/util/SourceRemapper.java
@@ -62,17 +62,12 @@ public class SourceRemapper {
 		this.toNamed = toNamed;
 	}
 
-	public static void remapSources(Project project, File input, File output, boolean named) throws Exception {
+	public static void remapSources(Project project, File input, File output, boolean named, boolean reproducibleFileOrder, boolean preserveFileTimestamps) {
 		SourceRemapper sourceRemapper = new SourceRemapper(project, named);
-		sourceRemapper.scheduleRemapSources(input, output, false, true);
+		sourceRemapper.scheduleRemapSources(input, output, reproducibleFileOrder, preserveFileTimestamps);
 		sourceRemapper.remapAll();
 	}
 
-	@Deprecated
-	public void scheduleRemapSources(File source, File destination) throws Exception {
-		scheduleRemapSources(source, destination, false, true); // Not reproducable by default, old behavior
-	}
-
 	public void scheduleRemapSources(File source, File destination, boolean reproducibleFileOrder, boolean preserveFileTimestamps) {
 		remapTasks.add((logger) -> {
 			try {
diff --git a/src/main/java/net/fabricmc/loom/util/ZipReprocessorUtil.java b/src/main/java/net/fabricmc/loom/util/ZipReprocessorUtil.java
index 662acf82..735b3346 100644
--- a/src/main/java/net/fabricmc/loom/util/ZipReprocessorUtil.java
+++ b/src/main/java/net/fabricmc/loom/util/ZipReprocessorUtil.java
@@ -29,11 +29,20 @@ import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
+import java.nio.file.attribute.FileTime;
+import java.util.Calendar;
+import java.util.Comparator;
+import java.util.GregorianCalendar;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;
 import java.util.zip.ZipOutputStream;
 
 public class ZipReprocessorUtil {
+	/**
+	 * See {@link org.gradle.api.internal.file.archive.ZipCopyAction} about this.
+	 */
+	private static final long CONSTANT_TIME_FOR_ZIP_ENTRIES = new GregorianCalendar(1980, Calendar.FEBRUARY, 1, 0, 0, 0).getTimeInMillis();
+
 	private ZipReprocessorUtil() { }
 
 	public static void reprocessZip(File file, boolean reproducibleFileOrder, boolean preserveFileTimestamps) throws IOException {
@@ -45,7 +54,7 @@ public class ZipReprocessorUtil {
 			ZipEntry[] entries;
 
 			if (reproducibleFileOrder) {
-				entries = zipFile.stream().sorted((a, b) -> a.getName().compareTo(b.getName())).toArray(ZipEntry[]::new);
+				entries = zipFile.stream().sorted(Comparator.comparing(ZipEntry::getName)).toArray(ZipEntry[]::new);
 			} else {
 				entries = zipFile.stream().toArray(ZipEntry[]::new);
 			}
@@ -54,11 +63,16 @@ public class ZipReprocessorUtil {
 
 			try (ZipOutputStream zipOutputStream = new ZipOutputStream(outZip)) {
 				for (ZipEntry entry : entries) {
+					ZipEntry newEntry = entry;
+
 					if (!preserveFileTimestamps) {
-						entry.setTime(0);
+						newEntry = new ZipEntry(entry.getName());
+						newEntry.setTime(CONSTANT_TIME_FOR_ZIP_ENTRIES);
+						newEntry.setLastModifiedTime(FileTime.fromMillis(CONSTANT_TIME_FOR_ZIP_ENTRIES));
+						newEntry.setLastAccessTime(FileTime.fromMillis(CONSTANT_TIME_FOR_ZIP_ENTRIES));
 					}
 
-					zipOutputStream.putNextEntry(entry);
+					zipOutputStream.putNextEntry(newEntry);
 					InputStream inputStream = zipFile.getInputStream(entry);
 					byte[] buf = new byte[1024];
 					int length;