Is java-policy normative? That is, is a violation of a "should" or
"must" clause in java-policy a "policy violation" and thus an RC bug?

My belief is not, because

a) it doesn't state in java-policy that it is a "sub-policy"
b) java-policy is not listed in debian-policy as a sub-policy
   <http://www.debian.org/doc/debian-policy/ch-scope.html#s-related>

By way of comparison, debian-policy makes explicit reference to the perl
sub-policy, but states "Perl programs and modules should follow the
current Perl policy" -- so violating the perl sub-policy is not
automatically RC (as "should" != "must" or "required").

Either way, some clarity in the java-policy would be useful (perhaps in
an "About this document" section). I'd have a stab at it myself, but I
am unclear which situation is correct :)

If it is desired that this is a sub-policy, some changes to
debian-policy would also be required.