FCPPluginClientTracker: Decide about backend data structure
- I would have prefered a O(1) structure which concurrent, unsynchronized get() (namely ConcurrentHashMap) instead of the O(n) get() TreeMap, but unfortunately Java does not offer auto-shrinking HashMaps. In theory I could have auto-replaced the HashMap with a fresh one if the load factor has shrunk too much, but that would have required synchronization. Also, it would be some work to implement, with little benefit: Currently, FCP is typically exposed to maybe 10 clients at once, so the speed difference would be not worth the effort.