code: private static Runnable asRunnable(final ClientTransport.PingCallback callback,
                                       final long roundTripTimeNanos) {
      return new Runnable() {
        @Override
        public void run() {
          callback.onSuccess(roundTripTimeNanos);
        }
      };
  
    }
docs: Returns a runnable that, when run, invokes the given callback, providing the given round-trip
  duration.