a) Should I really ought to be doing somethingYes, if you actually serialize those objects. It can make version maintenance easier.
properly with this field, and if so, can you advise
the best way to approach that.
b) Can I turn off these warnings. They are not in theYou turn them off on the Preferences | Compiler | Style page. It's the last item.
Eclipse filter to exclude.
c) Is it safe to ignore them?Sure. You just won't have as much control over serialized versions.