get logout working

fix issue with white screen after login

java/org/owasp/webgoat/controller/Logout.java

@@ -0,0 +1,45 @@
+/*
+ * To change this license header, choose License Headers in Project Properties.
+ * To change this template file, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package org.owasp.webgoat.controller;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.servlet.ModelAndView;
+
+/**
+ *
+ * @author rlawson
+ */
+@Controller
+public class Logout {
+
+    final Logger logger = LoggerFactory.getLogger(Logout.class);
+
+    @RequestMapping(value = "logout.do", method = RequestMethod.GET)
+    public ModelAndView logout(
+            @RequestParam(value = "error", required = false) String error,
+            @RequestParam(value = "logout", required = false) String logout) {
+        
+        logger.info("Logging user out");
+
+        ModelAndView model = new ModelAndView();
+        if (error != null) {
+            model.addObject("error", "Invalid username and password!");
+        }
+
+        if (logout != null) {
+            model.addObject("msg", "You've been logged out successfully.");
+        }
+        model.setViewName("logout");
+
+        return model;
+
+    }
+}