Need to pass a sample value in case of null value in webform data

Summary:

Hi I am trying to pass a null value in the form incase if user did not select any value in the lOV

in the form we have a used a table in that table we have used a select action and values we are populating in the select LOV from integration

and the scenario is like if user select the value from LOV and submit the transaction it will pass the exact value as user selects

in case if user did not select any value and submit the transaction i need to pass a value as NULL is it possible through events …