/**
* Registers (stores) a two-way mapping between this Event and this PipelineCacheKey for later
* retrieval.
*
* @param e The event to
* @param key key
*/
public void register(Event e, Serializable key) {
synchronized (this) {
m_keyMMap.put(key, e);
m_eventMMap.put(e, key);
}
}