simon, should we expose the getDefaultStopSet() as public yet, if you are planning on refactoring this stopword stuff in 3.1 anyway? (would you have to then deprecate this in 3.1?)
also, I'm not sure i like the copy() method in CharArraySet, i think it should return a real copy even if it is an EMPTY_SET, and if you give it a CharArraySet it should call .clone() ?
other things are minor, in Czech i think there is a spurious import added (javax.print.DocFlavor.CHAR_ARRAY), etc.
nothing to do with your issue, but maybe while we are here cleaning up these ctors we should fix the fact that a lot of these never call super() ?