fix(FormatExtension/Gradle): Fix step setup with toggleFence and targetExcludeContentPattern

With a non-null `toggleFence`, `com.diffplug.gradle.spotless.FormatExtension#setupTask` creates a new `List` via `List.of()`. Also having a non-null `targetExcludeContentPattern` leads to an `UnsupportedOperationException` thrown by `List.replaceAll`, because `List.of` yields an immutable list.

Change includes (integeration) tests.

Author: snazy

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

@@ -1061,7 +1061,9 @@ protected void setupTask(SpotlessTask task) {
 		task.setTarget(totalTarget);
 		List<FormatterStep> steps;
 		if (toggleFence != null) {
-			steps = List.of(toggleFence.preserveWithin(this.steps));
+			// need a mutable List, 'steps' is mutated by 'steps.replaceAll()' below
+			steps = new ArrayList<>();
+			steps.add(toggleFence.preserveWithin(this.steps));
 		} else {
 			steps = this.steps;
 		}

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

@@ -80,4 +80,56 @@ void removeUnusedImportsWithCleanthat() throws IOException {
 		gradleRunner().withArguments("spotlessApply").build();
 		assertFile("src/main/java/test.java").sameAsResource("java/removeunusedimports/Jdk17TextBlockFormatted.test");
 	}
+
+	/**
+	 * Triggers the special case in {@link FormatExtension#setupTask(SpotlessTask)} with {@code toggleFence} and
+	 * {@code targetExcludeContentPattern} both being not {@code null}.
+	 */
+	@Test
+	void fenceWithTargetExcludeNoMatch() throws Exception {
+		setFile("build.gradle").toLines(
+				"plugins {",
+				"  id 'com.diffplug.spotless'",
+				"  id 'java'",
+				"}",
+				"repositories { mavenCentral() }",
+				"",
+				"spotless {",
+				"  java {" +
+				"    licenseHeader('// my-copyright')",
+				"    toggleOffOn()",
+				"    targetExcludeIfContentContains('excludeMe')",
+				"  }",
+				"}");
+
+		setFile("src/main/java/test.java").toResource("java/targetExclude/TargetExcludeNoMatchUnformatted.test");
+		gradleRunner().withArguments("spotlessApply").build();
+		assertFile("src/main/java/test.java").sameAsResource("java/targetExclude/TargetExcludeNoMatchFormatted.test");
+	}
+
+	/**
+	 * Triggers the special case in {@link FormatExtension#setupTask(SpotlessTask)} with {@code toggleFence} and
+	 * {@code targetExcludeContentPattern} both being not {@code null}.
+	 */
+	@Test
+	void fenceWithTargetExcludeMatch() throws Exception {
+		setFile("build.gradle").toLines(
+				"plugins {",
+				"  id 'com.diffplug.spotless'",
+				"  id 'java'",
+				"}",
+				"repositories { mavenCentral() }",
+				"",
+				"spotless {",
+				"  java {" +
+				"    licenseHeader('// my-copyright')",
+				"    toggleOffOn()",
+				"    targetExcludeIfContentContains('excludeMe')",
+				"  }",
+				"}");
+
+		setFile("src/main/java/test.java").toResource("java/targetExclude/TargetExcludeMatch.test");
+		gradleRunner().withArguments("spotlessApply").build();
+		assertFile("src/main/java/test.java").sameAsResource("java/targetExclude/TargetExcludeMatch.test");
+	}
 }

testlib/src/main/resources/java/targetExclude/TargetExcludeMatch.test

@@ -0,0 +1,4 @@
+// excludeMe
+import foo.Bar;
+
+class Bar {}

testlib/src/main/resources/java/targetExclude/TargetExcludeNoMatchFormatted.test

@@ -0,0 +1,4 @@
+// my-copyright
+import foo.Bar;
+
+class Bar {}

testlib/src/main/resources/java/targetExclude/TargetExcludeNoMatchUnformatted.test

@@ -0,0 +1,3 @@
+import foo.Bar;
+
+class Bar {}