public void done() {
        done = true;
    }
GRPCStreamStatus is used for gRPC streaming client. It helps to make sure the gRPC client to wait the last streaming
has the onCompleted or onError confirmation.
oap-server/server-library/library-util/src/main/java/org/apache/skywalking/oap/server/library/util/GRPCStreamStatus.java