private JapaneseDate withYear(int year){
  return withYear(getEra(),year);
}

private JapaneseDate withYear ( int year ) { return withYear ( getEra ( ) , year ) ; }
returns a copy of this date with the year - of - era altered . < p > this method changes the year - of - era of the date . if the month - day is invalid for the year , then the previous valid day will be selected instead . < p > this instance is immutable and unaffected by this method call .
