code: public UnicodeSet applyPattern(String pattern, int options) {
          checkFrozen();
          return applyPattern(pattern, null, null, options);
      }
docs: Modifies this set to represent the set specified by the given pattern,
  optionally ignoring whitespace.
  See the class description for the syntax of the pattern language.
  @param pattern a string specifying what characters are in the set
  @param options a bitmask indicating which options to apply.
  Valid options are IGNORE_SPACE and CASE.
  @exception java.lang.IllegalArgumentException if the pattern
  contains a syntax error.