public function intermediate_image_sizes( $sizes = array() ) {
    
/** This filter is documented in wp-admin/includes/class-wp-site-icon.php */
    $this->site_icon_sizes = apply_filters( 'site_icon_image_sizes', $this->site_icon_sizes );
    foreach ( $this->site_icon_sizes as $size ) {
      $sizes[] = 'site_icon-' . $size;
    }

    return $sizes;
  }