Hi,
if you application needs javaassit then just include it yourself.
as for JPA and javaassit goes, it is bit more complex than just that.
jpa has dependancy to hibernate and hibernate has dependancy to javassist.
jpa --> hibernate --> javassist
and given that your application uses jpa, there is no need to directly include all transient depenencies.
if you application still needs javaassit but you do not explecitly use it anywhere it might be interesting case to looke more into detail.
Can you provide structure of your application (jar tf <name of ear>) and stacktrace you get. that will help find the couse of the issue.
--
tomaz