Oracle no longer supports using the EJBGen tags and code-generating tool on EJB 3.x beans. Rather, you can use this tool only on 2.x beans.
EJBGen is a tool to generate deployment descriptors.
Instead of editing and maintaining all of the multiple component files of an EJB, EJBGen lets you work with only one specially annotated bean class. From this one class, EJBGen parses the annotations and generates the remote and home interfaces and deployment descriptor. This is accomplished by using EJBGen annotations. These annotations are used to mark which methods are to be exposed when generating remote and home interfaces and to specify the deployment descriptor settings.