jet-engine-attachment-url-callback.php

<?php

add_filter( 'jet-engine/listings/allowed-callbacks', 'jet_add_attachment_callback', 10, 2 );

function jet_add_attachment_callback( $callbacks ) {
	$callbacks['jet_get_attachment_file'] = 'Get attachment file by ID';
	return $callbacks;
}

function jet_get_attachment_file( $attachment_id ) {
	return wp_get_attachment_url( $attachment_id );
}