code: @Override
      protected Map<String, String> getDefaultConfig(Map<String,String> pConfig) {
          Map<String,String> config = super.getDefaultConfig(pConfig);
          if (pConfig.containsKey("config")) {
              config.putAll(readConfig(pConfig.get("config")));
          }
          return config;
      }
docs: Beside reading the default configuration from an internal property file,
  also add extra configuration given in an external properties where the path
  to this property file is given under the key "config"
  
  @param pConfig the configuration provided during construction
  @return the default configuration used as fallback