Regarding EJB generation version, Plex only support versions 1.1 and 2.0. These two versions have final release dates 1999-12-17 and 2001-08-22 respectively.
The version 2.1 (with final release date from 2003-11-24) is not supported by Plex generator. So, Plex is frozen in time regarding EJB related issues.
We are actually using EJBs V2.0 in IBM WebSphere, but currently there are Application Servers that not support such an old EJB version. For example, we tried to deploy our application using IBM Liberty Profile but only EJB V3.0 or newer are supported. Note that EJB V3.0 is not new: it was released in 2006!
So, it is time to update Plex’ s EJB versions.