private function image_post_to_sitemap_item( $post ) {

    
/**
 * Filter condition to allow skipping specific image posts in the sitemap.
 *
 * @module sitemaps
 *
 * @since 4.8.0
 *
 * @param bool    $skip Current boolean. False by default, so no post is skipped.
 * @param WP_POST $post Current post object.
 */
    if ( apply_filters( 'jetpack_sitemap_image_skip_post', false, $post ) ) {
      return array(
        'xml'           => null,
        'last_modified' => null,
      );
    }

    $url = wp_get_attachment_url( $post->ID );

    // Do not include the image if the attached parent is not published.
    // Unattached will be published. Otherwise, will inherit parent status.
    if ( 'publish' !== get_post_status( $post ) ) {
      return array(
        'xml'           => null,
        'last_modified' => null,
      );
    }

    $parent_url = get_permalink( get_post( $post->post_parent ) );
    if ( '' == $parent_url ) { // WPCS: loose comparison ok.
      $parent_url = get_permalink( $post );
    }

    $item_array = array(
      'url' => array(
        'loc'         => $parent_url,
        'lastmod'     => jp_sitemap_datetime( $post->post_modified_gmt ),
        'image:image' => array(
          'image:loc' => $url,
        ),
      ),
    );

    $item_array['url']['image:image']['image:title']   = $post->post_title;
    $item_array['url']['image:image']['image:caption'] = $post->post_excerpt;

    
/**
 * Filter associative array with data to build <url> node
 * and its descendants for current post in image sitemap.
 *
 * @module sitemaps
 *
 * @since 4.8.0
 *
 * @param array $item_array Data to build parent and children nodes for current post.
 * @param int   $post_id Current image post ID.
 */
    $item_array = apply_filters(
      'jetpack_sitemap_image_sitemap_item',
      $item_array,
      $post->ID
    );

    return array(
      'xml'           => $item_array,
      'last_modified' => $post->post_modified_gmt,
    );
  }