Correct the gallery URL attachemnt field WordPress

gistfile1.aw

// Corrects the gallery URL attachment that disallows custom URLS
	// Use get_post_meta( ATTACHMENT_ID_HERE, '_wp_attachment_url', true ) to retrieve
	function _save_attachment_url($post, $attachment) {
	    if ( isset($attachment['url']) ) 
	        update_post_meta( $post['ID'], '_wp_attachment_url', esc_url_raw($attachment['url']) ); 
	    return $post;
	}
	add_filter('attachment_fields_to_save', '_save_attachment_url', 10, 2);
	
	function _replace_attachment_url($form_fields, $post) {
	    if ( isset($form_fields['url']['html']) ) {
	        $url = get_post_meta( $post->ID, '_wp_attachment_url', true );
	        if ( ! empty($url) )
	            $form_fields['url']['html'] = preg_replace( "/value='.*?'/", "value='$url'", $form_fields['url']['html'] );
	    }
	    return $form_fields;
	}
	add_filter('attachment_fields_to_edit', '_replace_attachment_url', 10, 2);