APT plugin for plain Java modules

JavaAptPlugin

import org.gradle.api.Plugin
import org.gradle.api.Project
import org.gradle.plugins.ide.idea.IdeaPlugin
import org.gradle.tooling.BuildException

class JavaAptPlugin implements Plugin<Project> {

    @Override
    void apply(Project project) {
        def aptConfiguration = project.configurations.create 'javapt'
        project.afterEvaluate {
            if (!project.plugins.hasPlugin('java')) {
              throw new BuildException("Project $project.name isn't a java project, can't apply javapt!", null)
            }
            project.apply(plugin: IdeaPlugin)
            configureProject(project, aptConfiguration)
        }
    }

    private void configureProject(Project project, def aptConfiguration) {
        File aptOutputDir = project.file('gen/javapt')
        project.sourceSets.main.compileClasspath += aptConfiguration

        // register generated sources with AndroidStudio
        project.idea.module {
            scopes.PROVIDED.plus += [aptConfiguration]
            sourceDirs += aptOutputDir
            generatedSourceDirs += aptOutputDir
        }

        //tweak compileJava task for annotation processing and clean generated output folder before compiling
        project.compileJava {
            outputs.file aptOutputDir
            options.compilerArgs += ['-s', aptOutputDir.absolutePath, '-processorpath', aptConfiguration.asPath]
            doFirst {
                aptOutputDir.deleteDir()
                aptOutputDir.mkdirs()
            }
        }

        // clean generated code when cleaning
        project.clean << {
            aptOutputDir.deleteDir()
        }
    }
}