string value of the authentication scheme used to protect the resource. If the resource is not
 authenticated, null is returned.

 Values are the same as the CGI variable AUTH_TYPE</div>
<dl class="notes">
<dt>Returns:</dt>
<dd>one of the static members BASIC_AUTH, FORM_AUTH, CLIENT_CERT_AUTH, DIGEST_AUTH (suitable for == comparison)
 or the container-specific string indicating the authentication scheme, or null if the request was not authenticated.</dd>
<dt>Throws:</dt>
<dd><code><a href="https://docs.orac