Attempts to modify, approve or change the state of a changeable resource will be handled by using optimistic concurrency checking. This implies that a user needs to first obtain a token for the update operation, and can only update a resource if the token is still valid.
Responses for changeable resources it will return
concurrencyToken property containing a value unique to the state of the resource.Any change request made using a PUT or DELETE action will require the
If-Match HTTP Request Header to be populated with the concurrency token value.The change request will be successfully processed only if the resource concurrency token value has not changed. If the resource state has changed,
412 - Precondition Failed will be returned.