public static <T> T doSynchronousClusterTask(ClusterTask<T> task, byte[] nodeID) {
        return cacheFactoryStrategy.doSynchronousClusterTask(task, nodeID);
    }
Invokes a task on a given cluster member synchronously and returns the result of
the remote operation. If clustering is not enabled, this method will return null.

@param task        the ClusterTask object to be invoked on a given cluster member.
@param nodeID      the byte array that identifies the target cluster member.
@param <T> the return type of the cluster task
@return result of remote operation or null if operation failed or operation returned null.
@throws IllegalStateException if requested node was not found or not running in a cluster.
xmppserver/src/main/java/org/jivesoftware/util/cache/CacheFactory.java