ClassNotFoundException with google-java-format 1.8

[benkard]

google-java-format 1.8 removes the feature to remove Javadoc-only imports (google/google-java-format@73c522a), but Spotless still tries to access the feature (

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

Line 128 in 0ab6802

Class<?> removeJavadocOnlyClass = classLoader.loadClass(REMOVE_UNUSED_IMPORT_JavadocOnlyImports);

). This causes an exception to be thrown when I attempt to use the Maven plugin with 1.8 as the google-java-format version:

com.google.googlejavaformat.java.RemoveUnusedImports$JavadocOnlyImports
java.lang.ClassNotFoundException: com.google.googlejavaformat.java.RemoveUnusedImports$JavadocOnlyImports
	at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:435)
	at com.diffplug.spotless.FeatureClassLoader.findClass(FeatureClassLoader.java:76)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:589)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
	at com.diffplug.spotless.java.GoogleJavaFormatStep$State.createFormat(GoogleJavaFormatStep.java:128)
	at com.diffplug.spotless.FormatterStepImpl$Standard.format(FormatterStepImpl.java:76)
	at com.diffplug.spotless.FormatterStep$Strict.format(FormatterStep.java:76)
	at com.diffplug.spotless.Formatter.compute(Formatter.java:230)
	at com.diffplug.spotless.Formatter.applyToAndReturnResultIfDirty(Formatter.java:192)
	at com.diffplug.spotless.Formatter.applyTo(Formatter.java:175)
	at com.diffplug.spotless.maven.SpotlessApplyMojo.process(SpotlessApplyMojo.java:45)
	at com.diffplug.spotless.maven.AbstractSpotlessMojo.execute(AbstractSpotlessMojo.java:127)
	at com.diffplug.spotless.maven.AbstractSpotlessMojo.execute(AbstractSpotlessMojo.java:120)
	at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:137)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:210)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:156)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:148)
	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:117)
	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:81)
	at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:56)
	at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:305)
	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:192)
	at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:105)
	at org.apache.maven.cli.MavenCli.execute(MavenCli.java:957)
	at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:289)
	at org.apache.maven.cli.MavenCli.main(MavenCli.java:193)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:564)
	at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:282)
	at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:225)
	at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:406)
	at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:347)

Configuration:

        <plugin>
          <groupId>com.diffplug.spotless</groupId>
          <artifactId>spotless-maven-plugin</artifactId>
          <version>1.30.0</version>
          <configuration>
            <java>
              <googleJavaFormat>
                <version>1.8</version>
                <style>GOOGLE</style>
              </googleJavaFormat>
            </java>
          </configuration>
        </plugin>

[nedtwigg]

Thanks for bug report! We've already got 1.1-specific code, we'll just need to add post-1.8 code.

Looks to me like we'll need to change these two places, this one:

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

Lines 128 to 130 in 608af5c

	Class<?> removeJavadocOnlyClass = classLoader.loadClass(REMOVE_UNUSED_IMPORT_JavadocOnlyImports);
	Object removeJavadocConstant = Enum.valueOf((Class<Enum>) removeJavadocOnlyClass, REMOVE_UNUSED_IMPORT_JavadocOnlyImports_Keep);
	Method removeUnusedMethod = removeUnusedClass.getMethod(REMOVE_UNUSED_METHOD, String.class, removeJavadocOnlyClass);

and this one:

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

Lines 148 to 150 in 608af5c

	Class<?> removeJavadocOnlyClass = classLoader.loadClass(REMOVE_UNUSED_IMPORT_JavadocOnlyImports);
	Object removeJavadocConstant = Enum.valueOf((Class<Enum>) removeJavadocOnlyClass, REMOVE_UNUSED_IMPORT_JavadocOnlyImports_Keep);
	Method removeUnusedMethod = removeUnusedClass.getMethod(REMOVE_UNUSED_METHOD, String.class, removeJavadocOnlyClass);

As for parsing that we're on a post-1.8 version, we've used simple regexes for that in the past:

spotless/lib/src/main/java/com/diffplug/spotless/kotlin/KtLintStep.java

Line 96 in 608af5c

Matcher matcher = VERSION_MATCHER.matcher(version);

spotless/lib/src/main/java/com/diffplug/spotless/scala/ScalaFmtStep.java

Lines 72 to 77 in 608af5c

	Matcher versionMatcher = VERSION_PRE_2_0.matcher(version);
	if (versionMatcher.matches()) {
	mavenCoordinate = MAVEN_COORDINATE_PRE_2_0;
	} else {
	mavenCoordinate = MAVEN_COORDINATE;
	}

Happy to take a PR for this. If the reflection is too messy, happy to take a PR for #524, which would make fixing this easier.

[benkard]

Created PR #563. Is the approach taken there OK?

[nedtwigg]

Thanks very much, code looks great. I tried adding a test, but google-java-format requires Java 11. The next eclipse formatter is going to require 11 as well. I'm gonna dabble a bit in this PR to figure out a way to cleanly get our CI going on both 8 and 11 for a while. We'll have your PR merged and shipped by Monday, ideally with CI, but if I don't finish in time we'll still get it out the door.

[benkard]

Thank you!