I have a hard time figuring out why Indexer#close() declares throwing Exceptions, while all it does is calling release(), which in turn cannot throw checked exceptions.

From my understanding, it is not expected from Indexer subclasses to override the close() method directly (none of them currently do). The current signature makes it a little painful to use Indexer instances within try-with-resource blocks, as opposed to what can be done with Pointer or PointerScope instances.