UI: Remove null properties from objects generated by json schema.

@@ -136,6 +136,7 @@ function Utils($mdColorPalette, $rootScope, $window, $translate, $q, $timeout, t
 
     var service = {
         getDefaultDatasource: getDefaultDatasource,
+        generateObjectFromJsonSchema: generateObjectFromJsonSchema,
         getDefaultDatasourceJson: getDefaultDatasourceJson,
         getDefaultAlarmDataKeys: getDefaultAlarmDataKeys,
         getMaterialColor: getMaterialColor,
@@ -277,11 +278,34 @@ function Utils($mdColorPalette, $rootScope, $window, $translate, $q, $timeout, t
     function getDefaultDatasource(dataKeySchema) {
         var datasource = angular.copy(defaultDatasource);
         if (angular.isDefined(dataKeySchema)) {
-            datasource.dataKeys[0].settings = jsonSchemaDefaults(dataKeySchema);
+            datasource.dataKeys[0].settings = generateObjectFromJsonSchema(dataKeySchema);
         }
         return datasource;
     }
 
+    function generateObjectFromJsonSchema(schema) {
+        var obj = jsonSchemaDefaults(schema);
+        deleteNullProperties(obj);
+        return obj;
+    }
+
+    function deleteNullProperties(obj) {
+        if (angular.isUndefined(obj) || obj == null) {
+            return;
+        }
+        for (var propName in obj) {
+            if (obj[propName] === null || angular.isUndefined(obj[propName])) {
+                delete obj[propName];
+            } else if (angular.isObject(obj[propName])) {
+                deleteNullProperties(obj[propName]);
+            } else if (angular.isArray(obj[propName])) {
+                for (var i=0;i<obj[propName].length;i++) {
+                    deleteNullProperties(obj[propName][i]);
+                }
+            }
+        }
+    }
+
     function getDefaultDatasourceJson(dataKeySchema) {
         return angular.toJson(getDefaultDatasource(dataKeySchema));
     }

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import jsonSchemaDefaults from 'json-schema-defaults';
+
 import thingsboardTypes from '../../common/types.constant';
 import thingsboardUtils from '../../common/utils.service';
 import thingsboardEntityAliasSelect from '../entity-alias-select.directive';
@@ -421,7 +421,7 @@ function WidgetConfig($compile, $templateCache, $rootScope, $translate, $timeout
             }
 
             if (angular.isDefined(scope.datakeySettingsSchema.schema)) {
-                result.settings = jsonSchemaDefaults(scope.datakeySettingsSchema.schema);
+                result.settings = utils.generateObjectFromJsonSchema(scope.datakeySettingsSchema.schema);
             }
 
             return result;