samples/xml/servletapi/src/main/java/org/springframework/security/samples/servletapi/mvc/ServletApiController.java
@RequestMapping("/authenticate")
	public String authenticate(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		boolean authenticate = request.authenticate(response);
		return authenticate ? "index" : null;
	}
@RequestMapping("/authenticate")
	public String authenticate(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		boolean authenticate = request.authenticate(response);
		return authenticate ? "index" : null;
	}
Demonstrates that {@link HttpServletRequest#authenticate(HttpServletResponse)} will
send the user to the log in page configured within Spring Security if the user is
not already authenticated.

@param request
@param response
@return
@throws ServletException
@throws IOException