Some refinements on top of PR #720

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/FormatExtension.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 DiffPlug
+ * Copyright 2016-2021 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -725,7 +725,7 @@ protected void setupTask(SpotlessTask task) {
 			spotless.getRegisterDependenciesTask().hookSubprojectTask(task);
 		}
 		if (getRatchetFrom() != null) {
-			task.setupRatchet(spotless.getRegisterDependenciesTask().gitRatchet, getRatchetFrom());
+			task.setupRatchet(spotless.getRegisterDependenciesTask().getGitRatchet().get(), getRatchetFrom());
 		}
 	}
 

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/GitRatchetGradle.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020 DiffPlug
+ * Copyright 2020-2021 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,11 +22,13 @@
 import org.gradle.api.Project;
 import org.gradle.api.services.BuildService;
 import org.gradle.api.services.BuildServiceParameters;
+import org.gradle.tooling.events.FinishEvent;
+import org.gradle.tooling.events.OperationCompletionListener;
 
 import com.diffplug.spotless.extra.GitRatchet;
 
 /** Gradle implementation of GitRatchet. */
-public abstract class GitRatchetGradle extends GitRatchet<Project> implements BuildService<BuildServiceParameters.None> {
+public abstract class GitRatchetGradle extends GitRatchet<Project> implements BuildService<BuildServiceParameters.None>, OperationCompletionListener {
 	@Override
 	protected File getDir(Project project) {
 		return project.getProjectDir();
@@ -36,4 +38,9 @@ protected File getDir(Project project) {
 	protected @Nullable Project getParent(Project project) {
 		return project.getParent();
 	}
+
+	@Override
+	public void onFinish(FinishEvent finishEvent) {
+		// NOOP
+	}
 }

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/RegisterDependenciesTask.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 DiffPlug
+ * Copyright 2016-2021 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,12 +21,17 @@
 import java.util.ArrayList;
 import java.util.List;
 
+import javax.inject.Inject;
+
 import org.gradle.api.DefaultTask;
 import org.gradle.api.execution.TaskExecutionGraph;
+import org.gradle.api.provider.Property;
+import org.gradle.api.provider.Provider;
 import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.Internal;
 import org.gradle.api.tasks.OutputFile;
 import org.gradle.api.tasks.TaskAction;
+import org.gradle.build.event.BuildEventsListenerRegistry;
 
 import com.diffplug.common.base.Preconditions;
 import com.diffplug.common.io.Files;
@@ -42,7 +47,7 @@
  * - When this "registerDependencies" task does its up-to-date check, it queries the task execution graph to see which
  *   SpotlessTasks are at risk of being executed, and causes them all to be evaluated safely in the root buildscript.
  */
-public class RegisterDependenciesTask extends DefaultTask {
+public abstract class RegisterDependenciesTask extends DefaultTask {
 	static final String TASK_NAME = "spotlessInternalRegisterDependencies";
 
 	@Input
@@ -87,7 +92,9 @@ void setup() {
 		Preconditions.checkArgument(getProject().getRootProject() == getProject(), "Can only be used on the root project");
 		unitOutput = new File(getProject().getBuildDir(), "tmp/spotless-register-dependencies");
 		rootProvisioner = new GradleProvisioner.RootProvisioner(getProject());
-		gitRatchet = getProject().getGradle().getSharedServices().registerIfAbsent("GitRatchetGradle", GitRatchetGradle.class, unused -> {}).get();
+		Provider<GitRatchetGradle> gitRatchetProvider = getProject().getGradle().getSharedServices().registerIfAbsent("GitRatchetGradle", GitRatchetGradle.class, unused -> {});
+		getBuildEventsListenerRegistry().onTaskCompletion(gitRatchetProvider);
+		getGitRatchet().set(gitRatchetProvider);
 	}
 
 	@TaskAction
@@ -96,10 +103,9 @@ public void trivialFunction() throws IOException {
 		Files.write(Integer.toString(getSteps().size()), unitOutput, StandardCharsets.UTF_8);
 	}
 
-	GitRatchetGradle gitRatchet;
-
 	@Internal
-	GitRatchetGradle getGitRatchet() {
-		return gitRatchet;
-	}
+	public abstract Property<GitRatchetGradle> getGitRatchet();
+
+	@Inject
+	protected abstract BuildEventsListenerRegistry getBuildEventsListenerRegistry();
 }

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/SpotlessPlugin.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 DiffPlug
+ * Copyright 2016-2021 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

plugin-gradle/src/test/java/com/diffplug/gradle/spotless/ConfigurationCacheTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020 DiffPlug
+ * Copyright 2020-2021 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

plugin-gradle/src/test/java/com/diffplug/gradle/spotless/GitRatchetGradleTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 DiffPlug
+ * Copyright 2016-2021 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

plugin-gradle/src/test/java/com/diffplug/gradle/spotless/GradleIntegrationHarness.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 DiffPlug
+ * Copyright 2016-2021 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

plugin-gradle/src/test/java/com/diffplug/gradle/spotless/SpotlessPluginRedirectTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020 DiffPlug
+ * Copyright 2020-2021 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.