Platform Release 25 January 2018
We published a tutorial about the API Extensions feature we recently released. The tutorial explains the usage of the feature based on two example use cases. In the first example an API Extension is developed that validates a maximum number of items that can be added to the cart. The extension developed in the second example will add a mandatory insurance to the cart if any item in the cart is worth $500 or more. Please check it out.
API Extensions can now return a localized description of the error. If available, the Merchant Center will use the correct localization to display the error.