code: private function getBlockFields(Content $content)
      {
          $fields = [];
  
          if ($this->blockFieldMapper->accept($content)) {
              $fields = $this->blockFieldMapper->mapFields($content);
          }
  
          return $fields;
      }
docs: Returns an array of fields for the given $content, to be added to the
  corresponding block documents.
  
  @param \eZ\Publish\SPI\Persistence\Content $content
  
  @return \eZ\Publish\SPI\Search\Field[]