code: public void applyAsSystemProperties (@Nullable final String... aPropertyNames)
    {
      if (isRead () && aPropertyNames != null)
        for (final String sProperty : aPropertyNames)
        {
          final String sConfigFileValue = getAsString (sProperty);
          if (sConfigFileValue != null)
          {
            SystemProperties.setPropertyValue (sProperty, sConfigFileValue);
            if (LOGGER.isInfoEnabled ())
              LOGGER.info ("Set Java system property from configuration: " + sProperty + "=" + sConfigFileValue);
          }
        }
    }
docs: This is a utility method, that takes the provided property names, checks if
  they are defined in the configuration and if so, applies applies them as
  System properties. It does it only when the configuration file was read
  correctly.
  
  @param aPropertyNames
  The property names to consider.
  @since 8.5.3