Finds the greatest key that is not greater than key, and its value.
public bool TryGetFloor(int key, scoped out int floorKey, [MaybeNullWhen(false)] scoped out CosObject value)
The key.
The greatest key in the tree not greater than key.
Its value, resolved one level.
true when the tree holds such a key.ISO 32000-2 §7.9.7. This is how a range keyed by its first number is found, as page labels are (§12.4.2). Reads the whole tree once, then answers from its index until the tree changes.