get https://virtserver.swaggerhub.com/singuladecisions/contracts/1.0.19/customer//contract//change/list
Get details of available subscriptions a customer's current contract can be crossgraded to.
Includes details of the initial and ongoing charges for the target subscription, but no estimate of the exact change cost.
This can be obtained by calling /customer/{customerId}/contract/{contractId}/change/cost for the specific target subscription