Remove Java files from default Maven Groovy formatting

All Groovy formatters will default to formatting only the following files:
 * src/main/groovy/**/*.groovy
 * src/test/groovy/**/*.groovy

They will not touch any .*java files.

Fixes #902.

Author: lutovich

plugin-maven/README.md

@@ -246,8 +246,6 @@ This is a workaround to a [pending issue](https://github.com/diffplug/spotless/i
     <includes>
       <include>src/main/groovy/**/*.groovy</include>
       <include>src/test/groovy/**/*.groovy</include>
-      <include>src/main/java/**/*.java</include>
-      <include>src/test/java/**/*.java</include>
     </includes>
 
     <importOrder /> <!-- standard import order -->

plugin-maven/src/main/java/com/diffplug/spotless/maven/groovy/Groovy.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.
@@ -29,7 +29,7 @@
  */
 public class Groovy extends FormatterFactory {
 
-	private static final Set<String> DEFAULT_INCLUDES = ImmutableSet.of("src/main/groovy/**/*.groovy", "src/test/groovy/**/*.groovy", "src/main/java/**/*.java", "src/test/java/**/*.java");
+	private static final Set<String> DEFAULT_INCLUDES = ImmutableSet.of("src/main/groovy/**/*.groovy", "src/test/groovy/**/*.groovy");
 	private static final String LICENSE_HEADER_DELIMITER = "package ";
 
 	@Override

plugin-maven/src/test/java/com/diffplug/spotless/maven/groovy/GrEclipseTest.java

@@ -15,6 +15,8 @@
  */
 package com.diffplug.spotless.maven.groovy;
 
+import java.io.IOException;
+
 import org.junit.jupiter.api.Test;
 
 import com.diffplug.spotless.maven.MavenIntegrationHarness;
@@ -23,16 +25,43 @@ class GrEclipseTest extends MavenIntegrationHarness {
 
 	@Test
 	void testEclipse() throws Exception {
-		writePomWithGroovySteps(
-				"<greclipse>",
-				"  <file>${basedir}/greclipse.properties</file>",
-				"  <version>4.12.0</version>",
-				"</greclipse>");
-		setFile("greclipse.properties").toResource("groovy/greclipse/format/greclipse.properties");
+		writePomWithGrEclipse();
 
 		String path = "src/main/groovy/test.groovy";
 		setFile(path).toResource("groovy/greclipse/format/unformatted.test");
 		mavenRunner().withArguments("spotless:apply").runNoError();
 		assertFile(path).sameAsResource("groovy/greclipse/format/formatted.test");
 	}
+
+	@Test
+	void doesNotFormatJavaFiles() throws Exception {
+		writePomWithGrEclipse();
+
+		String javaPath = "src/main/java/test.java";
+		String testJavaPath = "src/test/java/test.java";
+		setFile(javaPath).toResource("java/googlejavaformat/JavaCodeUnformatted.test");
+		setFile(testJavaPath).toResource("java/googlejavaformat/JavaCodeUnformatted.test");
+
+		String groovyPath = "src/main/groovy/test.groovy";
+		String testGroovyPath = "src/test/groovy/test.groovy";
+		setFile(groovyPath).toResource("groovy/greclipse/format/unformatted.test");
+		setFile(testGroovyPath).toResource("groovy/greclipse/format/unformatted.test");
+
+		mavenRunner().withArguments("spotless:apply").runNoError();
+
+		assertFile(javaPath).sameAsResource("java/googlejavaformat/JavaCodeUnformatted.test");
+		assertFile(testJavaPath).sameAsResource("java/googlejavaformat/JavaCodeUnformatted.test");
+
+		assertFile(groovyPath).sameAsResource("groovy/greclipse/format/formatted.test");
+		assertFile(testGroovyPath).sameAsResource("groovy/greclipse/format/formatted.test");
+	}
+
+	private void writePomWithGrEclipse() throws IOException {
+		writePomWithGroovySteps(
+				"<greclipse>",
+				"  <file>${basedir}/greclipse.properties</file>",
+				"  <version>4.19.0</version>",
+				"</greclipse>");
+		setFile("greclipse.properties").toResource("groovy/greclipse/format/greclipse.properties");
+	}
 }