code: public static <K, V> SortedMap<K, V> asImmutable(SortedMap<K, V> self) {
          return asUnmodifiable(new TreeMap<K, V>(self));
      }
docs: A convenience method for creating an immutable SortedMap.
  
  @param self a SortedMap
  @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.SortedMap)
  @since 1.0