If you did:

req.addClassFilter("a*");
req.addClassFilter("b*");

then this is:

(name.match("a*")) && (name.match("b*"))

And yes there would be no match. However,

req.addClassExclusionFilter("a*");
req.addClassExclusionFilter("b*");

then this is:

(!name.match("a*")) && (!name.match("b*"))

And anything that doesn't start "a" or "b" will pass.

The javadoc for addClassFilter doesn't say what happens if
it is called more than once.

It should be documented that you can use multiple filters and that they use "cut-off and".