WordPress at a glance
filter is not described

allow_empty_comment filter-hook . WP 5.1.0

Filters whether an empty comment should be allowed.


add_filter( 'allow_empty_comment', 'filter_function_name_6097', 10, 2 );
function filter_function_name_6097( $allow_empty_comment, $commentdata ){
	// filter...

	return $allow_empty_comment;
Whether to allow empty comments.
Default: false
Array of comment data to be sent to wp_insert_comment().

Where the hook is called

wp-includes/comment.php 3285
$allow_empty_comment = apply_filters( 'allow_empty_comment', false, $commentdata );

Where the hook is used (in WP core)

Does not used.