In 4.01 we introduced a delta patch mechanism that uses the delta payload to update a collection of entities.

Within the 4.01 delta payload, we support identifying an existing resource (for update or delete) by either the id, or the key properties.

Since alternate key properties can also be used to identify a resource, in 4.02 we should allow the use of alternate keys to identify an existing resource in a delta update payload for update or delete.