code: protected int toRegex(PatternAPI regex, Locale locale, String flags, char padding, int width, int precision, String formatString, int position) {
          throw new UnsupportedOperationException("Explicit width matching not supported.");
      }
docs: Appends a pattern to {@code pattern} that will be parsed into a value.
  If {@code with} is non-negative, it specifies the exact number of
  characters the pattern should consume.
  @param regex
  @param locale
  @param flags
  @param padding
  @param width
  @param precision
  @param formatString
  @param position
  @return