code: public static <T> SortedSet<T> asImmutable(SortedSet<T> self) {
          return asUnmodifiable(new TreeSet<T>(self));
      }
docs: A convenience method for creating an immutable SortedSet.
  
  @param self a SortedSet
  @return an unmodifiable view of a copy of the original, i.e. an effectively immutable copy
  @see #asImmutable(java.util.List)
  @see #asUnmodifiable(java.util.SortedSet)
  @since 1.0