have some initial default value to avoid NPE in onModified().
have some initial default value to avoid NPE in onModified().

This is a stop-gap fix to a bigger problem of XStream not persisting the owner of a persisted list.

git-svn-id: 28f34f9aa52bc55a5ddd5be9e183c5cccadc6ee4@34079 71c3de6d-444a-0410-be80-ed276b4c234a

stefanbrausch/hudson-main,stefanbrausch/hudson-main,stefanbrausch/hudson-main,stefanbrausch/hudson-main,stefanbrausch/hudson-main,stefanbrausch/hudson-main,stefanbrausch/hudson-main