Simple Beaver Builder Custom Post Property/Custom Field example. This example simply generates the permalink for the current post.

Beaver Builder Custom Post Property

/* Get the external link for each post, crate a new connection for custom post template 
 * The add_action will setup the post property so that it is selectable within Beaver Builder.
 * The function will grab and assign the value to the post property.
 * This example simple gets the current post permalink and returns/prints to screen.
*/
add_action( 'fl_page_data_add_properties', function() {

	FLPageData::add_post_property( 'll_permalink', array(
		'label'   => 'Post Permalink',
		'group'   => 'posts',
		'type'    => 'html',
		'getter'  => 'permalink_connection_getter',
	) );

} );

function permalink_connection_getter() {
	global $post;
	$post_id       = $post->ID;
	$post_slug=$post->post_name;
	$url = get_permalink( $post_id );
	$slug = $url;

    return $slug;
}