The problem with annotation it that it is not possible to easily understand what is in a .jar/.war/.ear file. There is a little tool in weblogic appmerge that will generate the equivalent deployment descriptors. You simply use the -writeInferredDescriptors parameter.
java weblogic.appmerge -writeInferredDescriptors -output output.war input.war
Have to admit not played with it yet as I just picked this from an internal mailing list; but it seems like a good tip for corner cases.