code: @Validate
      public void activate() {
          active = configuration.getBooleanWithDefault(CORS_FILTER_ENABLED, false);
          extraHeaders = configuration.getList(CORS_FILTER_ALLOW_HEADERS);
          allowedHosts = configuration.getList(CORS_FILTER_ALLOW_ORIGIN);
          allowCredentials = configuration.getBooleanWithDefault(CORS_FILTER_ALLOW_CREDENTIALS, false);
          if (configuration.has("cors.max-age")) {
              preflightMaxAge = configuration.getIntegerWithDefault(CORS_FILTER_MAX_AGE, 3600);
          }
  
      }
docs: Initialisation method. It checks whether the CORS support needs to be enabled or not.