docs: public void start() {
  		checkState(!closed, "The RPC connection is already closed");
  		checkState(!isConnected() && pendingRegistration == null, "The RPC connection is already started");
  
  		final RetryingRegistration<F, G, S> newRegistration = createNewRegistration();
  
  		if (REGISTRATION_UPDATER.compareAndSet(this, null, newRegistration)) {
  			newRegistration.startRegistration();
  		} else {
  			// concurrent start operation
  			newRegistration.cancel();
  		}
  	}