code: public function normalize($runValidation = true)
      {
          if ($runValidation && !$this->validate()) {
              return false;
          }
  
          $filter = $this->getFilter();
          if (!is_array($filter) || empty($filter)) {
              return [];
          }
  
          return $this->normalizeComplexFilter($filter);
      }
docs: Normalizes filter value, replacing raw keys according to [[filterControls]] and [[attributeMap]].
  @param bool $runValidation whether to perform validation (calling [[validate()]])
  before normalizing the filter. Defaults to `true`. If the validation fails, no filter will
  be processed and this method will return `false`.
  @return array|bool normalized filter value, or `false` if validation fails.