How to make a field required in WC Vendors Pro

functions.php

<?php 

// The first thing you need to do is find the filter for the field you want to adjust the requirements
// You can find the filters in public/forms/class-wcvendors-pro-product-form.php 

// You will need one of these for each field you'd like to make required. 
function make_required_fieldname( $args ) { 

    $args[ 'custom_attributes' ] => array( 
		 			'data-rules' => 'required', 
		 			'data-error' => __( 'This field is required.', 'wcvendors-pro' )
		 		); 
} 

// Using description as an example 
add_filter( 'wcv_product_description, 'make_required_fieldname' );