https://www.php.net/manual/en/eventhttprequest.getoutputheaders.php
PHP: EventHttpRequest::getOutputHeaders - Manual
Returns associative array of the output headers
phpmanual
https://www.php.net/manual/uk/eventhttprequest.getoutputheaders.php
PHP: EventHttpRequest::getOutputHeaders - Manual
Returns associative array of the output headers
phpmanual