Merge pull request #426 from bender316/master

feat(FeatureClassLoader): support class loading of Java 9+

CHANGES.md

@@ -7,6 +7,8 @@ You might be looking for:
 
 ### Version 1.25.0-SNAPSHOT - TBD (javadoc [lib](https://diffplug.github.io/spotless/javadoc/spotless-lib/snapshot/) [lib-extra](https://diffplug.github.io/spotless/javadoc/spotless-lib-extra/snapshot/), [snapshot repo](https://oss.sonatype.org/content/repositories/snapshots/com/diffplug/spotless/))
 
+* Fixes class loading issue with Java 9+ ([#426](https://github.com/diffplug/spotless/pull/426)).
+
 ### Version 1.24.0 - July 29th 2018 (javadoc [lib](https://diffplug.github.io/spotless/javadoc/spotless-lib/1.24.0/) [lib-extra](https://diffplug.github.io/spotless/javadoc/spotless-lib-extra/1.24.0/), artifact [lib]([jcenter](https://bintray.com/diffplug/opensource/spotless-lib), [lib-extra]([jcenter](https://bintray.com/diffplug/opensource/spotless-lib-extra)))
 
 * Updated default eclipse-wtp from 4.8.0 to 4.12.0 ([#423](https://github.com/diffplug/spotless/pull/423)).

lib/src/main/java/com/diffplug/spotless/FeatureClassLoader.java

@@ -22,6 +22,8 @@
 import java.util.List;
 import java.util.Objects;
 
+import javax.annotation.Nullable;
+
 /**
  * This class loader is used to load classes of Spotless features from a search
  * path of URLs.<br/>
@@ -59,7 +61,7 @@ class FeatureClassLoader extends URLClassLoader {
 	 */
 
 	FeatureClassLoader(URL[] urls, ClassLoader buildToolClassLoader) {
-		super(urls, null);
+		super(urls, getParentClassLoader());
 		Objects.requireNonNull(buildToolClassLoader);
 		this.buildToolClassLoader = buildToolClassLoader;
 	}
@@ -74,4 +76,25 @@ protected Class<?> findClass(String name) throws ClassNotFoundException {
 		return super.findClass(name);
 	}
 
+	/**
+	 * Making spotless Java 9+ compatible. In Java 8 (and minor) the bootstrap
+	 * class loader saw every platform class. In Java 9+ it was changed so the
+	 * bootstrap class loader does not see all classes anymore. This might lead
+	 * to ClassNotFoundException in formatters (e.g. freshmark).
+	 *
+	 * @return <code>null</code> on Java 8 (and minor), otherwise <code>PlatformClassLoader</code>
+	 */
+	@Nullable
+	private static ClassLoader getParentClassLoader() {
+		double version = Double.parseDouble(System.getProperty("java.specification.version"));
+		if (version > 1.8) {
+			try {
+				return (ClassLoader) ClassLoader.class.getMethod("getPlatformClassLoader").invoke(null);
+			} catch (Exception e) {
+				throw ThrowingEx.asRuntime(e);
+			}
+		} else {
+			return null;
+		}
+	}
 }

plugin-gradle/CHANGES.md

@@ -2,6 +2,8 @@
 
 ### Version 3.25.0-SNAPSHOT - TBD ([javadoc](https://diffplug.github.io/spotless/javadoc/snapshot/), [snapshot](https://oss.sonatype.org/content/repositories/snapshots/com/diffplug/spotless/spotless-plugin-gradle/))
 
+* Fixes class loading issue with Java 9+ ([#426](https://github.com/diffplug/spotless/pull/426)).
+
 ### Version 3.24.0 - July 29th 2019 ([javadoc](https://diffplug.github.io/spotless/javadoc/spotless-plugin-gradle/3.24.0/), [jcenter](https://bintray.com/diffplug/opensource/spotless-plugin-gradle/3.24.0))
 
 * Updated default eclipse-wtp from 4.8.0 to 4.12.0 ([#423](https://github.com/diffplug/spotless/pull/423)).

plugin-maven/CHANGES.md

@@ -2,6 +2,8 @@
 
 ### Version 1.25.0-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/))
 
+* Fixes class loading issue with Java 9+ ([#426](https://github.com/diffplug/spotless/pull/426)).
+
 ### Version 1.24.0 - July 29th 2019 ([javadoc](https://diffplug.github.io/spotless/javadoc/spotless-maven-plugin/1.24.0/), [jcenter](https://bintray.com/diffplug/opensource/spotless-maven-plugin/1.24.0))
 
 * Updated default eclipse-wtp from 4.8.0 to 4.12.0 ([#423](https://github.com/diffplug/spotless/pull/423)).