### Bug report

The MultiColumnComboBox is initialized without a specified value. When the user focuses on the widget and leaves it without selecting or entering an option, the "cascade" event is fired.

### Reproduction of the problem

1) Create a MultiColumnComboBox and initialize it without a value;

2) Subscribe to the "cascade" event after the initialization of the widget;

3) Focus the input;

4) Leave it;

5) The "cascade" event is triggered on "blur".

A Dojo sample for reproduction: https://dojo.telerik.com/EViKaXaZ

### Expected/desired behavior

The "cascade" event should fire when changing the widget's value via API or user interaction.

### Environment

* **Kendo UI version: 2021.3.914
* **jQuery version: 1.12.4
* **Browser: [all]