I needed CharArraySet.clear() for something I was working on in Solr in a tokenstream.
instead I ended up using CharArrayMap<Boolean> because it supported .clear()
it would be better to use a set though, currently it will throw UOE for .clear() because AbstractSet will call iterator.remove() which throws UOE.
In Solr, the very similar CharArrayMap.clear() looks like this:
I think we can do a similar thing as long as we throw UOE for the UnmodifiableCharArraySet
will submit a patch later tonight (unless someone is bored and has nothing better to do)