code: public SC registerServletContextListener(Class<? extends ServletContextListener> servletContextListener) {
          __throwIfInitialized();
  
          if (servletContextListener == null)
              throw new IllegalArgumentException("Event listener cannot be null");
  
          servletContextListenerSet.add(servletContextListener);
  
          return (SC) this;
      }
docs: Registers an EventListener.
  
  @param servletContextListener ServletContextListener subclass to be registered.
  @return this