code: public static final BigInteger printDurationTimeUnits(Duration duration, boolean estimated)
     {
        // SF-329: null default required to keep Powerproject happy when importing MSPDI files
        TimeUnit units = duration == null ? PARENT_FILE.get().getProjectProperties().getDefaultDurationUnits() : duration.getUnits();
        return printDurationTimeUnits(units, estimated);
     }
docs: Print duration time units.
  
  @param duration Duration value
  @param estimated is this an estimated duration
  @return time units value