code: public Duration minusHours(long hoursToSubtract) {
          return (hoursToSubtract == Long.MIN_VALUE ? plusHours(Long.MAX_VALUE).plusHours(1) : plusHours(-hoursToSubtract));
      }
docs: Returns a copy of this duration with the specified duration in hours subtracted.
  <p>
  The number of hours is multiplied by 3600 to obtain the number of seconds to subtract.
  <p>
  This instance is immutable and unaffected by this method call.
  
  @param hoursToSubtract  the hours to subtract, positive or negative
  @return a {@code Duration} based on this duration with the specified hours subtracted, not null
  @throws ArithmeticException if numeric overflow occurs