code: public function resolve() {
          if (is_null($this->config->getDisplayField()) || $this->config->getDisplayField() == '') {
              $this->config->setDisplayField($this->resolveDisplayField());
              $this->config->setVisibleFields($this->resolveVisibleFields());
          }
  
          return $this->config;
      }
docs: Resolves a Config instance.
  
  @return ModelConfig The resolved config.