Remove isAndroid check from setupExtractIncludeProtosTask

Have Java and Android pass in the appropriate objects instead of looking
them up. This was the last isAndroid check in ProtobufPlugin excepting
apply() itself.

Author: ejona86

src/main/groovy/com/google/protobuf/gradle/ProtobufPlugin.groovy

@@ -234,8 +234,12 @@ class ProtobufPlugin implements Plugin<Project> {
         Configuration compileProtoPath, Collection<Closure> postConfigure) {
       Provider<ProtobufExtract> extractProtosTask =
           setupExtractProtosTask(sourceSet.name, protobufConfig)
+      // In Java projects, the compileClasspath of the 'test' sourceSet includes all the
+      // 'resources' of the output of 'main', in which the source protos are placed.  This is
+      // nicer than the ad-hoc solution that Android has, because it works for any extended
+      // configuration, not just 'testCompile'.
       Provider<ProtobufExtract> extractIncludeProtosTask = setupExtractIncludeProtosTask(
-          sourceSet.name, false, compileProtoPath)
+          sourceSet.name, compileProtoPath, sourceSet.compileClasspath)
       Provider<GenerateProtoTask> generateProtoTask = addGenerateProtoTask(
           sourceSet.name, protoSrcDirSet.sourceDirectories, project.files(extractProtosTask),
           extractIncludeProtosTask) {
@@ -290,15 +294,23 @@ class ProtobufPlugin implements Plugin<Project> {
             it.attribute(artifactType, "jar")
         }
       }.files
-      FileCollection testClassPathConfig =
-          variant.hasProperty("testedVariant") ?
-            variant.testedVariant.compileConfiguration.incoming.artifactView {
+      FileCollection testClassPathConfig = project.objects.fileCollection()
+      if (Utils.isTest(variant.name)) {
+        // TODO(zhangkun83): Android sourceSet doesn't have compileClasspath. If it did, we
+        // haven't figured out a way to put source protos in 'resources'. For now we use an
+        // ad-hoc solution that manually includes the source protos of 'main' and its
+        // dependencies.
+        testClassPathConfig = project.android.sourceSets['main'].proto.sourceDirectories
+        if (variant.hasProperty("testedVariant")) {
+          testClassPathConfig += variant.testedVariant.compileConfiguration.incoming.artifactView {
                 attributes {
                     it.attribute(artifactType, "jar")
                 }
-            }.files : null
+              }.files
+        }
+      }
       Provider<ProtobufExtract> extractIncludeProtosTask =
-          setupExtractIncludeProtosTask(variant.name, true, classPathConfig, testClassPathConfig)
+          setupExtractIncludeProtosTask(variant.name, classPathConfig, testClassPathConfig)
 
       // GenerateProto task, one per variant (compilation unit).
       FileCollection sourceDirs = project.files(project.providers.provider {
@@ -417,40 +429,23 @@ class ProtobufPlugin implements Plugin<Project> {
      *
      * <p>This task is per-sourceSet for both Java and per variant for Android.
      */
-    @TypeChecked(TypeCheckingMode.SKIP) // Don't depend on AGP
     private Provider<ProtobufExtract> setupExtractIncludeProtosTask(
         String sourceSetOrVariantName,
-        boolean isAndroid,
         FileCollection compileClasspathConfiguration,
-        FileCollection testedCompileClasspathConfiguration = null) {
+        FileCollection testedCompileClasspathConfiguration) {
       String extractIncludeProtosTaskName = 'extractInclude' +
           Utils.getSourceSetSubstringForTaskNames(sourceSetOrVariantName) + 'Proto'
       return project.tasks.register(extractIncludeProtosTaskName, ProtobufExtract) {
         it.description = "Extracts proto files from compile dependencies for includes"
-        it.destDir = getExtractedIncludeProtosDir(sourceSetOrVariantName) as File
+        it.destDir.set(getExtractedIncludeProtosDir(sourceSetOrVariantName) as File)
         it.inputFiles.from(compileClasspathConfiguration)
 
         // TL; DR: Make protos in 'test' sourceSet able to import protos from the 'main'
         // sourceSet.  Sub-configurations, e.g., 'testCompile' that extends 'compile', don't
         // depend on the their super configurations. As a result, 'testCompile' doesn't depend on
         // 'compile' and it cannot get the proto files from 'main' sourceSet through the
-        // configuration. However,
-        if (isAndroid) {
-          // TODO(zhangkun83): Android sourceSet doesn't have compileClasspath. If it did, we
-          // haven't figured out a way to put source protos in 'resources'. For now we use an
-          // ad-hoc solution that manually includes the source protos of 'main' and its
-          // dependencies.
-          if (Utils.isTest(sourceSetOrVariantName)) {
-            it.inputFiles.from project.android.sourceSets['main'].proto.sourceDirectories
-            it.inputFiles.from testedCompileClasspathConfiguration
-          }
-        } else {
-          // In Java projects, the compileClasspath of the 'test' sourceSet includes all the
-          // 'resources' of the output of 'main', in which the source protos are placed.  This is
-          // nicer than the ad-hoc solution that Android has, because it works for any extended
-          // configuration, not just 'testCompile'.
-          it.inputFiles.from project.sourceSets[sourceSetOrVariantName].compileClasspath
-        }
+        // configuration.
+        it.inputFiles.from(testedCompileClasspathConfiguration)
       }
     }