title: Woocommerce Create custom product type with variations
body: <p>I have a plugin of booking that create a new product type of WC_Product. I'll like to change this booking product type for variable booking product type (new product type of WC_Product_Variation or WC_Product_Variable), but have somenthings errors when change this product type to variable.</p>
  
  <p><a href="https://i.stack.imgur.com/soKXO.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/soKXO.png" alt=""></a></p>
  
  <p>Thanks</p>