code: public static <E, S extends SortedSet<E>> SynchronizedSortedSet<E> of(S set)
      {
          return new SynchronizedSortedSet<E>(SortedSetAdapter.adapt(set));
      }
docs: This method will take a MutableSortedSet and wrap it directly in a SynchronizedSortedSet.  It will
  take any other non-GS-collection and first adapt it will a SortedSetAdapter, and then return a
  SynchronizedSortedSet that wraps the adapter.