1 # static mixed http\Env::getRequestHeader([string $header_name])
3 Retrieve one or all headers of the current HTTP request.
7 * Optional string $header_name
8 The key of a header to retrieve.
12 * NULL, if $header_name was not found
13 * string, the compound header when $header_name was found
14 * array of all headers if $header_name was not specified