I'm mapping a bean with a java.util.List type property where the bean getter returns a read-only view of the list via Collections.unmodifiableList(original). org.jboss.beans.metadata.plugins.AbstractCollectionMetaData#getValue fails here with a deployment exception since the method does not ensure the collection instance supports the optional Collection.add() operation (and doesn't fall back to default collection) *** DEPLOYMENTS IN ERROR: Name -> Error Manager -> java.lang.UnsupportedOperationException It seems rather unintuitive that the MC requires the read-method to provide a mutable collection reference and proceeds to make changes to my collection via read-method access? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4060208#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...