@Override
	public DBCachedObjectStoreKeySubSet descendingSet() {
		return new DBCachedObjectStoreKeySubSet(store, errHandler, lock,
			Direction.reverse(direction), keySpan);
	}
This is the sub-ranged form of {@link DBCachedObjectStoreKeySubSet}

<p>
For example, this can be obtained via {@code store.asMap().subMap(...).keySet()} or
{@code map.keySet().subSet(...)}.
Ghidra/Debug/ProposedUtils/src/main/java/ghidra/util/database/DBCachedObjectStoreKeySubSet.java