code: public YearQuarter minusQuarters(long quartersToSubtract) {
          return (quartersToSubtract == Long.MIN_VALUE ? plusQuarters(Long.MAX_VALUE).plusQuarters(1) : plusQuarters(-quartersToSubtract));
      }
docs: Returns a copy of this year-quarter with the specified period in quarters subtracted.
  <p>
  This instance is immutable and unaffected by this method call.
  
  @param quartersToSubtract  the quarters to subtract, may be negative
  @return a {@code YearQuarter} based on this year-quarter with the quarters subtracted, not null
  @throws DateTimeException if the result exceeds the supported range