duplicate key: interface javax.validation.constraints.Size

I got this error from JBoss while playing with RichFaces 4:

duplicate key: interface javax.validation.constraints.Size

JBoss and RichFaces 4 are not to blame - I am. I realized I switched RichFaces 4 versions (from 4.0.0.Final to 4.0.1-SNAPSHOT) and deployed both with my WAR file. So if you get this error, perhaps that’s what you should look into first.