@Override
    public void writeExternal(ObjectOutput out) throws IOException {
        ExternalizableUtil.getInstance().writeByteArray(out, nodeID);
    }
Class which wraps the byte[] we use to identify cluster members. The main reason
for this class is that byte[] cannot be directly compared so having a collection
of byte[] is not possible since you cannot remove to equivalent byte[] from the
collection.<p>

@author Pete Matern
@author Gaston Dombiak
xmppserver/src/main/java/org/jivesoftware/openfire/cluster/NodeID.java