code: public DateTimeFormatterBuilder appendTwoDigitYear(int pivot, boolean lenientParse) {
          return append0(new TwoDigitYear(DateTimeFieldType.year(), pivot, lenientParse));
      }
docs: Instructs the printer to emit a numeric year field which always prints
  two digits. A pivot year is used during parsing to determine the range
  of supported years as <code>(pivot - 50) .. (pivot + 49)</code>. If
  parse is instructed to be lenient and the digit count is not two, it is
  treated as an absolute year. With lenient parsing, specifying a positive
  or negative sign before the year also makes it absolute.
  
  @param pivot  pivot year to use when parsing
  @param lenientParse  when true, if digit count is not two, it is treated
  as an absolute year
  @return this DateTimeFormatterBuilder, for chaining
  @since 1.1