remove extra space

Signed-off-by: Jimmy Tanagra <jcode@tanagra.id.au>

Author: jimtng

bundles/org.openhab.core.model.item/src/org/openhab/core/model/validation/ItemsValidator.xtend

@@ -70,7 +70,7 @@ class ItemsValidator extends AbstractItemsValidator {
 
     @Check
     def checkValidGroupFunction(ModelGroupItem item) {
-        if (item.function !==  null && !GroupFunction.VALID_FUNCTIONS.contains(item.function)) {
+        if (item.function !== null && !GroupFunction.VALID_FUNCTIONS.contains(item.function)) {
 			error("Invalid group function: " + item.function, ItemsPackage.Literals.MODEL_GROUP_ITEM__FUNCTION)
         }
     }