code: public void addResponseFilter(String name, ResponseFilter responseFilter) {
      if (responseFilters.containsKey(name)) {
        throw new IllegalArgumentException("Duplicate response filter: " + name);
      }
      proxy.addResponseFilter(responseFilter);
      responseFilters.put(name, responseFilter);
    }
docs: Add a custom response filter which allows to track/modify all server responses to browser
  
  @param name unique name of filter
  @param responseFilter the filter