XWiki.getURLContent Proxy Authentication fails if proxy asks for NTLM, BASIC Authentication

In Extension Manager, in the case where the proxy can do NTLM and tells it's priority is NTML, then BASIC

XWiki will fail to allow to force usage of BASIC authentication and will use NTLM and fail authentication.

A workaround works forcing BASIC auth using the following code:

       List prefs = new ArrayList(1);
       prefs.add(AuthPolicy.BASIC);
       client.getParams().setParameter(AuthPolicy.AUTH_SCHEME_PRIORITY, prefs);

This issue also happens for in Extension Manager (XWIKI-11835)