No license headers for package-info and module-info in Maven (#273)

* No license headers for package-info and module-info in Maven

These two files are currently not supported by the license header
step and might get formatted incorrectly.

This commit makes Maven plugin exclude both `package-info.java`
and `module-info.java`.

* Update changelog

Author: lutovich

plugin-maven/CHANGES.md

@@ -2,6 +2,8 @@
 
 ### Version 1.15.0-SNAPSHOT - TBD ([javadoc](https://diffplug.github.io/spotless/javadoc/spotless-maven-plugin/snapshot/), [snapshot](https://oss.sonatype.org/content/repositories/snapshots/com/diffplug/spotless/spotless-maven-plugin/))
 
+* Skip `package-info.java` and `module-info.java` files from license header formatting. ([#273](https://github.com/diffplug/spotless/pull/273))
+
 ### Version 1.14.0 - July 24th 2018 ([javadoc](https://diffplug.github.io/spotless/javadoc/spotless-maven-plugin/1.14.0/), [jcenter](https://bintray.com/diffplug/opensource/spotless-maven-plugin/1.14.0))
 
 * Updated default eclipse-jdt from 4.7.2 to 4.7.3a ([#263](https://github.com/diffplug/spotless/issues/263)). New version fixes a bug preventing Java code formatting within JavaDoc comments ([#191](https://github.com/diffplug/spotless/issues/191)).

plugin-maven/src/main/java/com/diffplug/spotless/maven/generic/LicenseHeader.java

@@ -20,11 +20,16 @@
 import org.apache.maven.plugins.annotations.Parameter;
 
 import com.diffplug.spotless.FormatterStep;
+import com.diffplug.spotless.SerializableFileFilter;
 import com.diffplug.spotless.generic.LicenseHeaderStep;
 import com.diffplug.spotless.maven.FormatterStepConfig;
 import com.diffplug.spotless.maven.FormatterStepFactory;
 
 public class LicenseHeader implements FormatterStepFactory {
+
+	private static final SerializableFileFilter UNSUPPORTED_FILES_FILTER = SerializableFileFilter.skipFilesNamed(
+			"package-info.java", "module-info.java");
+
 	@Parameter
 	private String file;
 
@@ -42,14 +47,22 @@ public final FormatterStep newFormatterStep(FormatterStepConfig config) {
 		}
 
 		if (file != null ^ content != null) {
-			if (file != null) {
-				File licenseHeaderFile = config.getFileLocator().locateFile(file);
-				return LicenseHeaderStep.createFromFile(licenseHeaderFile, config.getEncoding(), delimiterString);
-			} else {
-				return LicenseHeaderStep.createFromHeader(content, delimiterString);
-			}
+			FormatterStep step = file != null
+					? createStepFromFile(config, delimiterString)
+					: createStepFromContent(delimiterString);
+
+			return step.filterByFile(UNSUPPORTED_FILES_FILTER);
 		} else {
 			throw new IllegalArgumentException("Must specify exactly one of 'file' or 'content'.");
 		}
 	}
+
+	private FormatterStep createStepFromFile(FormatterStepConfig config, String delimiterString) {
+		File licenseHeaderFile = config.getFileLocator().locateFile(file);
+		return LicenseHeaderStep.createFromFile(licenseHeaderFile, config.getEncoding(), delimiterString);
+	}
+
+	private FormatterStep createStepFromContent(String delimiterString) {
+		return LicenseHeaderStep.createFromHeader(content, delimiterString);
+	}
 }

plugin-maven/src/test/java/com/diffplug/spotless/maven/generic/LicenseHeaderTest.java

@@ -97,10 +97,37 @@ public void fromContentKotlin() throws Exception {
 		assertFile(path).hasContent(KOTLIN_LICENSE_HEADER + '\n' + noLicenseHeader);
 	}
 
+	@Test
+	public void unsupportedPackageInfo() throws Exception {
+		testUnsupportedFile("package-info.java");
+	}
+
+	@Test
+	public void unsupportedModuleInfo() throws Exception {
+		testUnsupportedFile("module-info.java");
+	}
+
 	private void runTest() throws Exception {
 		String path = "src/main/java/test.java";
 		setFile(path).toResource("license/MissingLicense.test");
 		mavenRunner().withArguments("spotless:apply").runNoError();
 		assertFile(path).sameAsResource("license/HasLicense.test");
 	}
+
+	private void testUnsupportedFile(String file) throws Exception {
+		writePomWithJavaSteps(
+				"<licenseHeader>",
+				"  <content>",
+				"// Hello!",
+				"  </content>",
+				"</licenseHeader>");
+
+		String path = "src/main/java/com/diffplug/spotless/" + file;
+		setFile(path).toResource("license/" + file);
+
+		mavenRunner().withArguments("spotless:apply").runNoError();
+
+		// file should remain the same
+		assertFile(path).sameAsResource("license/" + file);
+	}
 }

testlib/src/main/resources/license/module-info.java

@@ -0,0 +1,6 @@
+module com.diffplug.spotless {
+
+    requires com.diffplug.durian;
+
+    exports com.diffplug.spotless;
+}

testlib/src/main/resources/license/package-info.java

@@ -0,0 +1,8 @@
+/**
+ * Test package-info.java file.
+ * <p>
+ * Used only by integration tests.
+ *
+ * @since 1.0
+ */
+package com.diffplug.spotless;