docs: public void setSelectedSystemProperties (final Set <String> aCollection)
    {
      selectedSystemProperties = new HashSet <> ();
      if (aCollection != null)
      {
        for (final String sName : aCollection)
          if (StringHelper.hasText (sName))
            if (!selectedSystemProperties.add (sName))
              getLog ().warn ("The selected system property '" + sName + "' is contained more than once");
      }
      if (!selectedSystemProperties.isEmpty ())
      {
        // If we have a set of selected, don't use all system properties
        if (withAllSystemProperties)
        {
          getLog ().warn ("Disabling all system properties, because selected system properties are defined!");
          setWithAllSystemProperties (false);
        }
      }
    }