Update Inbound Shipping Method of an Exchange

Add an Inbound Shipping Method to an Exchange POST

Add an inbound (or return) shipping method to an exchange. The inbound shipping method will have a `SHIPPING_ADD` action.

Remove Inbound Shipping Method from Exchange DELETE

Remove the shipping method for returning items in the exchange using the `ID` of the method's `SHIPPING_ADD` action. Every shipping method has an `actions` property, whose value is an array of actions. You can check the action's name using its `action` property, and use the value of the `id` property.