how to use plexus-maven-plugin to both generate and merge descriptor ?

[nicolas de loof]

Hi
according to plexus doc, the plexus-maven-plugin has a merge goal
(process-resources phase) and an descriptor goal (process-classes phase)

Based on declared phases, It seems not possible to merge with the generated
descriptor, is it ?
Why does descriptor set process-classes phase and not generate-resources ??)