added property groupingTypeIdchanged the getGroupingTypeId to return the groupingTypeId instead of using the "instanceOf" checksadded method isRandomGrouping() , isChosenGrouping() and isClassGrouping()
added the property groupingTypeId, which previously wasnt there.when retrieving Grouping objects, the groupingTypeId was null regardless of what value was stored on database. Works okay now.
Modified the "leaveToolSession" and related code to allow the tool to pass the userid (which it gets from UserDTO in the shared session) rather than pass User (which the tool doesn't have).
changed libraryActivityUiImage to libraryActivityUIImagefor any properties that are null, it will return null, instead of sending the special null value