function filter_fields( $response ) {
    if ( empty( $this->query['fields'] ) || ( is_array( $response ) && ! empty( $response['error'] ) ) || ! empty( $this->endpoint->custom_fields_filtering ) ) {
      return $response;
    }

    $fields = array_map( 'trim', explode( ',', $this->query['fields'] ) );

    if ( is_object( $response ) ) {
      $response = (array) $response;
    }

    $has_filtered = false;
    if ( is_array( $response ) && empty( $response['ID'] ) ) {
      $keys_to_filter = array(
        'categories',
        'comments',
        'connections',
        'domains',
        'groups',
        'likes',
        'media',
        'notes',
        'posts',
        'services',
        'sites',
        'suggestions',
        'tags',
        'themes',
        'topics',
        'users',
      );

      foreach ( $keys_to_filter as $key_to_filter ) {
        if ( ! isset( $response[ $key_to_filter ] ) || $has_filtered ) {
          continue;
        }

        foreach ( $response[ $key_to_filter ] as $key => $values ) {
          if ( is_object( $values ) ) {
            if ( is_object( $response[ $key_to_filter ] ) ) {
              $response[ $key_to_filter ]->$key = (object) array_intersect_key( ( (array) $values ), array_flip( $fields ) );
            } elseif ( is_array( $response[ $key_to_filter ] ) ) {
              $response[ $key_to_filter ][ $key ] = (object) array_intersect_key( ( (array) $values ), array_flip( $fields ) );
            }
          } elseif ( is_array( $values ) ) {
            $response[ $key_to_filter ][ $key ] = array_intersect_key( $values, array_flip( $fields ) );
          }
        }

        $has_filtered = true;
      }
    }

    if ( ! $has_filtered ) {
      if ( is_object( $response ) ) {
        $response = (object) array_intersect_key( (array) $response, array_flip( $fields ) );
      } elseif ( is_array( $response ) ) {
        $response = array_intersect_key( $response, array_flip( $fields ) );
      }
    }

    return $response;
  }