Good!
It answers also to the thread "messageformat error blows up (JBSEAM-1859)"
http://www.jboss.com/index.html?module=bb&op=viewtopic&t=117235
May I suggest that, in place of the partial result of interpolation, the wrong message is also shown to the user by returning it in the catch block:
log.warn("exception interpolating string: " + string, e);
return string;
It gives then a direct clue that something is wrong. And it's already the way to do thing in other
cases of wrong syntax (see "messageformat error blows up" test in InterpolatorTest)
