No we don't have that today.
Imagine an index that has A, B and an old C or even some D data put in there by Lucene access directly.
If you purgeAll(A.class);purgeAll(B.class); then C and D are still in the index.
With my proposal, C and D would be gone too.

Got you. However, how do you know about C and D. I think one would literally have to look at the basedir on the filesystem (provided this is even possible given the directory type)