RE: isSupported12.xml

I think it is probably highly unlikely that an implementation would throw an exception for a known but unsupported feature but not throw an exception for a totally wacky feature.  However, if
isSupported is going to be tested for all known features, then you should add a wacky feature and version to cover the more likely failure of throwing an exception for an unrecognized or "malformed"
feature or version.

I've been putting <!-- ISSUE  --> comments in tests that I think need to have an errata to resolve (which would be the case here).