Seam-gen and groovy

I recently added a groovy action class to my seam-gen project. After a while eclipse’s auto-build kept giving me these misleading ant errors in the groovy.compilemodel task:

groovyc doesn't support the "srcdir" attribute

It took me a while to fix this issue. When i ran the compile target manually there was no problem, so eventually i figured it had to do with the explode launcher that was generated by seam-gen. You need to let it run in a separate JVM.
First, right-click on the project and select “Properties”.

Properties for open18

Next, select “Builders” and Edit the explode builder.

Edit Configuration
Edit configuration

Finally, click the “JRE” tab en select “Separate JRE” as the runtime JRE.

After this the auto-build error should be gone.