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

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

        message.setTargetId((short) -1);
        publicationForShards.offer(message.asUnsafeBuffer());
    }
@Override
    protected synchronized void sendCoordinationCommand(VoidMessage message) {
        if (nodeRole == NodeRole.SHARD && voidConfiguration.getNumberOfShards() == 1) {
            message.setTargetId((short) -1);
            messages.add(message);
            return;
        }

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

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

@param message