1. ensure that all query methods in task service makes use of callback, if not registered it will result in no-op
2. mark query methods with group ids as deprecated and provide new ones that entirely rely on callback
3. enhance Default callback implementation to cover default scenario, to read up the groups and build a simple store for them internally, that will result in same behavior as now
4. provide JAAS based callback for local task service
5. provide Database callback implementation