Enhancement
There should be an API with which several subject objects can be deleted at once.
Implementation
The service method
KBUtils#deleteAll(Iterable<? extends TLObject>)
was introduced to delete multiple tl:TLObject's. This uses the actual API
KnowledgeBase#deleteAll(Collection<? extends KnowledgeItem>)
to delete all given tl:KnowledgeItem.
Test
TestDBKnowledgeBase#testMassiveItemOperations()