Kapt3: Add generated source files to Java compile task after kapt execution. Filter only .java files.

This is needed to generate Kotlin files using kapt.

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/internal/Kapt3KotlinGradleSubplugin.kt

@@ -157,8 +157,6 @@ class Kapt3KotlinGradleSubplugin : KotlinGradleSubplugin<KotlinCompile> {
 
         kaptClasspath.forEach { pluginOptions += SubpluginOption("apclasspath", it.absolutePath) }
 
-        javaCompile.source(generatedFilesDir)
-
         pluginOptions += SubpluginOption("sources", generatedFilesDir.canonicalPath)
         pluginOptions += SubpluginOption("classes", getKaptClasssesDir(project, sourceSetName).canonicalPath)
 
@@ -204,6 +202,7 @@ class Kapt3KotlinGradleSubplugin : KotlinGradleSubplugin<KotlinCompile> {
         val kaptTaskName = kotlinCompile.name.replaceFirst("compile", "kapt")
         val kaptTask = project.tasks.create(kaptTaskName, KaptTask::class.java)
         kaptTask.kotlinCompileTask = kotlinCompile
+        kaptTask.javaCompileTask = javaCompile
         kotlinToKaptTasksMap[kotlinCompile] = kaptTask
 
         project.resolveSubpluginArtifacts(listOf(this@Kapt3KotlinGradleSubplugin)).flatMap { it.value }.forEach {
@@ -218,7 +217,6 @@ class Kapt3KotlinGradleSubplugin : KotlinGradleSubplugin<KotlinCompile> {
 
         // Add generated source dir as a source root for kotlinCompile and javaCompile
         kotlinCompile.source(sourcesOutputDir)
-        javaCompile.source(sourcesOutputDir)
         variantData?.let {
             if (AndroidGradleWrapper.isJackEnabled(it)) {
                 AndroidGradleWrapper.addSourceToJack(it, sourcesOutputDir)

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/internal/KaptTask.kt

@@ -15,8 +15,6 @@ import org.jetbrains.kotlin.gradle.tasks.*
 import org.jetbrains.kotlin.incremental.classpathAsList
 import org.jetbrains.kotlin.incremental.destinationAsFile
 import java.io.File
-import java.net.URLDecoder
-import java.nio.charset.Charset
 
 open class KaptTask : AbstractCompile() {
     private val rawSourceRoots = FilteringSourceRootsContainer({ !it.isInsideDestinationDir() })
@@ -24,6 +22,7 @@ open class KaptTask : AbstractCompile() {
 
     internal val pluginOptions = CompilerPluginOptions()
     internal lateinit var kotlinCompileTask: KotlinCompile
+    internal lateinit var javaCompileTask: AbstractCompile
 
     override fun setSource(sources: Any?) {
         val filteredSources = rawSourceRoots.set(sources)
@@ -75,5 +74,7 @@ open class KaptTask : AbstractCompile() {
         val compilerRunner = GradleCompilerRunner(project)
         val exitCode = compilerRunner.runJvmCompiler(sourceRoots.kotlinSourceFiles, sourceRoots.javaSourceRoots, args, environment)
         throwGradleExceptionIfError(exitCode)
+
+        javaCompileTask.source(destinationDir.walkTopDown().filter { it.extension == "java" }.toList())
     }
 }