Is it possible to read http/2 request header fields?

I am trying to retrieve the request header (I do not want to modify it) and see what the GET parameters were by retrieving the :path property. I have read on StackOverflow and other websites about it, but no concrete answer was ever given as to whether this is possible or not. So hereby the question: Is it possible and if so, how?

For example, using the following (PHP) code does not return the properties starting with ::

$headers = apache_request_headers();

foreach ($headers as $header => $value) {
   echo "$header: $value <br />\n";
}
 echo "<br/>";
 echo "<br/>";