code: public Period minusMonths(long monthsToSubtract) {
          return (monthsToSubtract == Long.MIN_VALUE ? plusMonths(Long.MAX_VALUE).plusMonths(1) : plusMonths(-monthsToSubtract));
      }
docs: Returns a copy of this period with the specified months subtracted.
  <p>
  This subtracts the amount from the months unit in a copy of this period.
  The years and days units are unaffected.
  For example, "1 year, 6 months and 3 days" minus 2 months returns "1 year, 4 months and 3 days".
  <p>
  This instance is immutable and unaffected by this method call.
  
  @param monthsToSubtract  the years to subtract, positive or negative
  @return a {@code Period} based on this period with the specified months subtracted, not null
  @throws ArithmeticException if numeric overflow occurs