public function getHeader($name)
    {
        $key = $this->headerKey($name);
        if (array_key_exists($key, $this->headers)) {
            return $this->headers[$key];
        }

        return [];
    }
public function getHeader($name)
    {
        $key = $this->headerKey($name);
        if (array_key_exists($key, $this->headers)) {
            return $this->headers[$key];
        }

        return [];
    }
public function getHeader ( $ name ) { $ key = $ this -> headerKey ( $ name ) ; if ( array_key_exists ( $ key , $ this -> headers ) ) { return $ this -> headers [ $ key ] ; } return [ ] ; }
Retrieves a message header value by the given case-insensitive name.

This method returns an array of all the header values of the given
case-insensitive header name.

If the header does not appear in the message, this method MUST return an
empty array.

@param string $name Case-insensitive header field name.
@return string[] An array of string values as provided for the given
header. If the header does not appear in the message, this method MUST
return an empty array.
Retrieves a message header value by the given case - insensitive name .