Add a sourceSet for generated code

[andrewkroh]

The plugin should add a new sourceSet for the generated code so that it is automatically incorporated into your IDE. I will also address that in the next release.

As a workaround you can add a sourceSet yourself. This will get the source into your IDE, but it does not wire up a dependency on the compileProto task.

sourceSets {
  generated {
    java.srcDirs += "$buildDir/$protobuf.outputJava"
  }
}