I’ve been doing some work with the DITA Open Toolkit 1.5 lately, and got no love from Google on this issue, so here’s my contribution to anyone else who finds it:
If you are trying to build and get an error like:
Then check the version of your Java. I got this error with Java 1.5, and resolved it by switching to Java 1.6.
I’ll have something more to post about DITA soon, but I just thought I’d get that out there for anyone else who is scouring Google in vain.