### Bug report

When the Form contains multiple Upload editros, which are required, the Form's validator validates only the first Upload editor.

### Reproduction of the problem

1) Create a Form with two Upload editors.

2) Make both Uploads required.

3) Submit the Form without uploaded files.

4) The validation for required triggers only for the first Upload editor.

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

### Expected/desired behavior

All Upload editors in the Form must be validated.

### Workaround

• Handle the Validate event of the Form.
• Verify if the "StartingFile" Upload contains a file for upload using the getFiles() method.
• Call the validateInput() method of the Form's Validator on the "StartingFile" input element to trigger the validation.

function onValidate(e) {
        var uploadComponent = $("#StartingFile").data("kendoUpload"); // get a reference to the Upload editor
        var form = e.sender;
        var validator = form.validator;
        if (uploadComponent.getFiles().length == 0) { // check the selected files for upload
            validator.validateInput($("input[name='StartingFile']")); // trigger the "required" validation, if no files are selected for upload
        }
}

### Environment

* **Kendo UI version: 2025.2.702
* **jQuery version: 3.7.1
* **Browser: [all]