Expose the field documentFieldLocationMapping of the DefaultValueListManager

The DefaultValueListManager has the field documentFieldLocationMapping is private and has no getter.
I would like to access the map. My usecase is this:
In my BaseComponent I put all available selectionlists on the request. Off course the lists are cached.
If I could read the documentFieldLocationMapping I would have access to the available identifiers. Currently I override the DefaultValueListManager just to copy a reference to the map.

I propose a getter wich returns an unmodifiable version of the HashMap.

Also I noticed that the DefaultValueListManager contains a reference to deprecated method: getAvailableTranslationsBean. That might be another improvement.