jbInit();
ServerGridDataLocator gridLocator = new ServerGridDataLocator();
gridLocator.setServerMethodName("loadItemVariants");
varGrid.setGridDataLocator(gridLocator);
varGrid.setController(new GridController() {
/**
* Method invoked when the user has clicked on save button and the grid is in EDIT mode.
* @param rowNumbers row indexes related to the changed/new rows
* @param oldPersistentObjects old value objects, previous the changes; it can contains null objects, in case of new inserted rows