code: public long currentTimeInMillis() {
  
          if (this.monotonic || MONOTON_MODE) {
              long nanos = this.utcNanos();
              long secs = LeapSeconds.getInstance().strip(Math.floorDiv(nanos, MRD));
              return Math.multiplyExact(secs, 1000) + Math.floorMod(nanos, MIO);
          } else {
              return System.currentTimeMillis();
          }
  
      }
docs: /*[deutsch]
  <p>Liefert die aktuelle seit [1970-01-01T00:00:00,000Z] verstrichene
  Zeit in Millisekunden. </p>
  
  @return  count of milliseconds since UNIX epoch without leap seconds
  @see     #currentTimeInMicros()