It is not possible to declare a working combined closure/aggregate table in the mondrian schema.
Mondrian expects such closure dimensions to create a 'peer' dimension for domensions with a closure table. For a dimension with a closure called 'Employees' the peer dimension will be called 'Employees$Closure'. This peer dimension is only referenced back to the source dimension at the closure level of the hierarchy.
The ExplicitRecognizer is used to match <AggName> element declared in the schema. The ExplicitMatcher scans registered hierarchies to determine whether the explicitly declared hierarchy is part of the cube. Because the 'peer' hierarchy is not actually linked in as a dimension on the cube (but only a peer to the level), it does not appear as a candidate level for the aggregation, and thus the explicitly declared hierarchy Employees$Closure is not recognized, and the aggregation table fails to be recognized as a candiddate for the cube.
This causes an error, and no aggregation is available.
QA Impact: Dev will give repro steps, make sure it works as expected. QA will also test the current documentation to make sure it is accurate.
Doc Impact: None ... It's documented but it doesn't work. Might have impact if the doc has to be changed.