code: public MachineTime<U> abs() {
  
          if (this.isNegative()) {
              return new MachineTime<>(Math.negateExact(this.seconds), -this.nanos, this.scale);
          } else {
              return this;
          }
  
      }
docs: /*[deutsch]
  <p>Wandelt eine maschinelle Dauer in ihren Absolutbetrag um. </p>
  
  @return  absolute machine time duration, always non-negative
  @throws  ArithmeticException in case of numerical overflow
  @since   2.0