Hi Jochen,
Now, there is no extension entry for doing that. if you want to add an addition elResovler, you have to re-write org.jbpm.pvm.internal.script.JuelScriptEngine. There is a method named makeResovler().
private ELResolver makeResolver()
{
CompositeELResolver chain = new CompositeELResolver();
chain.add(new ArrayELResolver());
chain.add(new ListELResolver());
chain.add(new MapELResolver());
chain.add(new ResourceBundleELResolver());
chain.add(new BeanELResolver());
return new SimpleResolver(chain);
}
Add whatever you want to.
Good Luck.