/**
 * Callback function for the 'webmention_handler_mf2_set_properties' filter.
 *
 * @param array $array 
 * @param mixed $this 
 * @return array The filtered value.
 */
function my_webmention_handler_mf2_set_properties_callback( array $array, $this ) {
    // Your code here.
    return $array;
}
add_filter( 'webmention_handler_mf2_set_properties', 'my_webmention_handler_mf2_set_properties_callback', 10, 2 );

apply_filters( 'webmention_handler_mf2_set_properties', array(), $this )