On the contrary, `$this->_env` is initialized with `$this->_config['env']` (`$_ENV` + `$_SERVER` when `globals` is true) in the `__construct()` method.

All HTTP headers (at least in most server configurations of nginx and apache) end up in `$_SERVER` as `$_SERVER['HTTP_HEADER_NAME']` so a call utilizing `$this->env()` magic isn't necessary.  We just want the raw input from the environment variables.