docs: @Override
      public void contextInitialized(ServletContextEvent sce) {
          ServletContext context = sce.getServletContext();
          String propertiesConfig = context.getInitParameter(PROPERTIES_CONFIG);
          if(propertiesConfig == null) {
              propertiesConfig = PROPERTIES_CONFIG_DEFAULT;
          }
          SystemProperties config = loadConfiguration(propertiesConfig, context);
          addProperties(config);
          if(config.getFile() != null) {
              addPropertiesFromFile(config, context);
          }
          
      }