android/guava/src/com/google/common/collect/ForwardingSortedSet.java
@Beta
  protected SortedSet<E> standardSubSet(E fromElement, E toElement) {
    return tailSet(fromElement).headSet(toElement);
  }
@Beta
  protected SortedSet<E> standardSubSet(E fromElement, E toElement) {
    return tailSet(fromElement).headSet(toElement);
  }
A sensible default implementation of {@link #subSet(Object, Object)} in terms of {@link
#headSet(Object)} and {@link #tailSet(Object)}. In some situations, you may wish to override
{@link #subSet(Object, Object)} to forward to this implementation.

@since 7.0