nd4j-parameter-server-parent/nd4j-parameter-server-node/src/main/java/org/nd4j/parameterserver/distributed/transport/MulticastTransport.java
@Override
    protected synchronized void sendFeedbackToClient(VoidMessage message) {
        if (nodeRole == NodeRole.SHARD && voidConfiguration.getNumberOfShards() == 1
                        && message instanceof MeaningfulMessage) {
            message.setTargetId((short) -1);
            completed.put(message.getTaskId(), (MeaningfulMessage) message);
            return;
        }

        //log.info("Sending FC: {}", message.getClass().getCanonicalName());

        message.setTargetId((short) -1);
        publicationForClients.offer(message.asUnsafeBuffer());
    }
@Override
    protected synchronized void sendFeedbackToClient(VoidMessage message) {
        if (nodeRole == NodeRole.SHARD && voidConfiguration.getNumberOfShards() == 1
                        && message instanceof MeaningfulMessage) {
            message.setTargetId((short) -1);
            completed.put(message.getTaskId(), (MeaningfulMessage) message);
            return;
        }

        //log.info("Sending FC: {}", message.getClass().getCanonicalName());

        message.setTargetId((short) -1);
        publicationForClients.offer(message.asUnsafeBuffer());
    }
This command is possible to issue only from Shard

@param message