just verified that 3.2.2RC4 behaves the same way as 3.2.2RC3 with regards to adding the column index before declaring the foreign key constraint, as it should. thus, i now have more evidence for considering the absence of this behaviour in 3.2.2 a bug.
Have a look at the release notes for JBoss-3.2.2:
Removed ADD INDEX from FK constraint template for mySQL. It does not work for compound keys.
Maybe you could fix it for yourself ;-).
my bad for not consulting the release notes :-) [was a bit difficult finding them however, once i knew of their existence].
but your explanation points the way for me to temporarily fix my problem while still using 3.2.2 --- creating a modified mySQL type-mapping in my app's META-INF/jbosscmp-jdbc.xml, which essentially reverts back to the old 3.2.2RC4-style foreign-key constraint template. i tested that this works, so that's what i'll continue doing for now.
to fix things so that the server's default jbosscmp-jdbc.xml works for both composite keys and my simple integer keys may require some slight architecture change in jboss, right? i'd be glad to discuss and look into it when i have some more free time.