Make changes to remove VS2015 sematic in test code

Author: chinadragon0515

test/ODataEndToEnd/Microsoft.OData.Service.Library/DataStoreManager/DefaultDataStoreManager.cs

@@ -147,7 +147,13 @@ public void StopTimer()
             private Timer InitTimer()
             {
                 DataStoreTimer = new Timer(_dataStoreLifeTime);
-                DataStoreTimer.Elapsed += (sender, args) => { _timerTimeoutHandler?.Invoke(this, args); };
+                DataStoreTimer.Elapsed += (sender, args) =>
+                {
+                    if (_timerTimeoutHandler != null)
+                    {
+                        _timerTimeoutHandler.Invoke(this, args);
+                    }
+                };
                 DataStoreTimer.Start();
                 return DataStoreTimer;
             }

test/ODataEndToEnd/Microsoft.OData.Service.Library/Utils/LibraryUtils.cs

@@ -8,7 +8,12 @@ public static class LibraryUtils
         static public string GetSessionId()
         {
             var session = System.Web.HttpContext.Current.Session;
-            return session?.SessionID;
+            if (session != null)
+            {
+                return session.SessionID;
+            }
+
+            return null;
         }
     }
 }