code: public void send(final long identifier, final SpecificRecord message) {
      if (sender != null) {
        sender.onNext(serializer.write(message, identifier));
      } else {
        final String msgClassName = message.getClass().getCanonicalName();
        LOG.log(Level.SEVERE, "Attempt to send message [{0}] before network is initialized", msgClassName);
        throw new RuntimeException("NetworkTransport not initialized: failed to send " + msgClassName);
      }
    }
docs: Sends a message to the C# side of the bridge.
  @param message An Avro message class derived from SpecificRecord.
  @throws RuntimeException if invoked before initialization is complete.