IPersonAttributeDao implementation that simply returns the attributes with which it is invoked. If you ask it for the attributes for "awp9", it returns the map "uid"->"awp9". If you ask it for user attributes given some other Map, it returns that Map.
The expected usage of this object is as the first child IPersonAttributeDao of a CascadingPersonAttributeDao instance. This has the effect of retaining the attributes with which the CascadingPersonAttributeDao is invoked in the Map returned from the CascadingPersonAttributeDao instance.