@Override
	public DBCachedObjectStoreKeySubSet headSet(Long toElement, boolean inclusive) {
		KeySpan span = KeySpan.head(toElement, inclusive, direction);
		return new DBCachedObjectStoreKeySubSet(store, errHandler, lock, direction,
			keySpan.intersect(span));
	}
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