public function changeDefaultBookCover() {

		$post = $this->getMetaPost();

		if ( $post ) {
			$pb_cover_image = get_post_meta( $post->ID, 'pb_cover_image', true );
			if ( preg_match( '~assets/images/default-book-cover\.png$~', $pb_cover_image ) ) {
				update_post_meta( $post->ID, 'pb_cover_image', \Pressbooks\Image\default_cover_url() );
				Book::deleteBookObjectCache();
			}
		}
	}