private void mergeMessage(final M message, final MessageCombiner<M> messageCombiner) {
        if (this.incomingMessages.isEmpty() || null == messageCombiner)
            this.incomingMessages.add(message);
        else
            this.incomingMessages.set(0, messageCombiner.combine(this.incomingMessages.get(0), message));
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
spark-gremlin/src/main/java/org/apache/tinkerpop/gremlin/spark/process/computer/payload/ViewIncomingPayload.java