code: public final UnicodeSet applyPattern(String pattern) {
          checkFrozen();
          return applyPattern(pattern, null, null, IGNORE_SPACE);
      }
docs: Modifies this set to represent the set specified by the given pattern.
  See the class description for the syntax of the pattern language.
  Whitespace is ignored.
  @param pattern a string specifying what characters are in the set
  @exception java.lang.IllegalArgumentException if the pattern
  contains a syntax error.