@java.lang.Override
    @java.lang.SuppressWarnings("unchecked")
    public io.grpc.stub.StreamObserver<Req> invoke(
        io.grpc.stub.StreamObserver<Resp> responseObserver) {
      switch (methodId) {
        case METHODID_STREAMING_SYNTHESIZE:
          return (io.grpc.stub.StreamObserver<Req>)
              serviceImpl.streamingSynthesize(
                  (io.grpc.stub.StreamObserver<
                          com.google.cloud.texttospeech.v1.StreamingSynthesizeResponse>)
                      responseObserver);
        default:
          throw new AssertionError();
      }
    }
<pre>
Synthesizes speech synchronously: receive results after all text input
has been processed.
</pre>
java-texttospeech/grpc-google-cloud-texttospeech-v1/src/main/java/com/google/cloud/texttospeech/v1/TextToSpeechGrpc.java