docs: public void doFilter(ResourceRequest request, ResourceResponse response, FilterChain chain) throws IOException,
              PortletException {
  
          // Lazily initialize the delegate if necessary.
          initDelegate(true);
  
          if (this.resourceDelegate == null) {
              throw new IllegalStateException("The delegate PortletFilter does not implement ResourceFilter but " + this.getFilterName() + " is configured with the RESOURCE_PHASE lifecycle.");
          }
  
          // Let the delegate perform the actual doFilter operation.
          invokeDelegate(this.resourceDelegate, request, response, chain);
      }