We do also have the same problem.
Even if the res-sharing-sope is set to "Unsharable" JBoss 7 uses connections in a sharable way.
It seems that JBoss 7 dosn't support this mandatory feature.
From my point of view this is a bug of JBoss 7.
Sorry, I can't help you, because I'm not member of the developer comunity.
Regards Martin.