fix issues with initial null strings

Author: tschie

src/main/java/com/esri/samples/map/create_and_save_map/CreateAndSaveMapController.java

@@ -104,7 +104,7 @@ private void initialize() {
 
       @Override
       public String toString(PortalFolder folder) {
-        return folder.getTitle();
+        return folder != null ? folder.getTitle() : "";
       }
 
       @Override

src/main/java/com/esri/samples/map/open_map_url/OpenMapURLSample.java

@@ -87,7 +87,7 @@ public void start(Stage stage) throws Exception {
 
       @Override
       public String toString(ArcGISMap map) {
-        return map.getItem().getTitle();
+        return map != null ? map.getItem().getTitle() : "";
       }
 
       @Override

src/main/java/com/esri/samples/na/offline_routing/OfflineRoutingSample.java

@@ -105,7 +105,7 @@ public void start(Stage stage) throws Exception {
         @Override
         public String toString(TravelMode travelMode) {
 
-          return travelMode.getName();
+          return travelMode != null ? travelMode.getName() : "";
         }
 
         @Override