code: @Override
  	public void setAttribute(final String name, Object value) {
  		if (HttpContext.AUTHENTICATION_TYPE.equals(name)) {
  			handleAuthenticationType(value);
  		} else if (HttpContext.REMOTE_USER.equals(name)) {
  			handleRemoteUser(value);
  		}
  		super.setAttribute(name, value);
  	}
docs: Filter the setting of authentication related attributes. If one of
  HttpContext.AUTHENTICATION_TYPE or HTTPContext.REMOTE_USER set the
  corresponding values in original request.
  
  @see javax.servlet.http.HttpServletRequest#setAttribute(String, Object)