Custom product attributes is blank even though I add it

Question

I try to add a post meta for the product attribute but its not showing in product. It creates but blank both field names and values. How should I fix this? there are no errors

Sample Code for updating/insert woocommerce product attributes

update_post_meta( $post->ID , '_product_attributes', [
                'name' => 'Size',
                'value' => 'S|M|L',
                'position' => 0,
                'is_visible' => 1,
                'is_variation' => 1,
                'is_taxonomy' => 1  
            ] );

Output Image

I didn't see that missing array needed. Solution below.

update_post_meta( $post->ID , '_product_attributes', [
                'size' => [
                     'name' => 'Size',
                     'value' => 'S|M|L',
                     'position' => 0,
                     'is_visible' => 1,
                     'is_variation' => 1,
                     'is_taxonomy' => 1 
                 ]

            ] );