code: public Moment minus(
          long amount,
          SI unit
      ) {
  
          return this.plus(Math.negateExact(amount), unit);
  
      }
docs: /*[deutsch]
  <p>Subtrahiert einen Betrag in der angegegebenen Zeiteinheit von der
  UTC-Zeit dieses Zeitstempels. </p>
  
  @param   amount  amount in SI-units to be subtracted
  @param   unit    time unit defined in UTC time space
  @return  changed copy of this instance
  @throws  UnsupportedOperationException if either this moment or the result are before 1972
  @throws  ArithmeticException in case of overflow