code: public MessagePattern parsePluralStyle(String pattern) {
          preParse(pattern);
          parsePluralOrSelectStyle(ArgType.PLURAL, 0, 0);
          postParse();
          return this;
      }
docs: Parses a PluralFormat pattern string.
  @param pattern a PluralFormat pattern string
  @return this
  @throws IllegalArgumentException for syntax errors in the pattern string
  @throws IndexOutOfBoundsException if certain limits are exceeded
  (e.g., argument number too high, argument name too long, etc.)
  @throws NumberFormatException if a number could not be parsed