docs: protected static void loadConfigSource(ConfigArgP config, String source) {
      Properties p = loadConfig(source);
      Config c = config.getConfig();
      for(String key: p.stringPropertyNames()) {
        String value = p.getProperty(key);
        ConfigurationItem ci = config.getConfigurationItem(key);      
        if(ci!=null) { // if we recognize the key, validate it
          ci.setValue(processConfigValue(value));
        }
        c.overrideConfig(key, processConfigValue(value));     
      }
    }