This issue is not due to circular dependency, but due to the fact that Ant is trying to create Customer class, which needs a reference to Job class. Since Job class is not yet created we have this error.
I would suggest, you change the order so that, Job class (without any depenency) gets generated first and then Customer class (with dependency on Job) gets generated next.
This way we should be able to generate the Java code.
You can run before you walk