Problem:
We received feedback on potential race conditions in the new REST API that we need to think about how to address. The feedback was:
PUT actions appear dangerous due to race conditions. For example, what happens if the entity has changed by client B between client A reading an entity with GET /entities/items and then client A attempting to replace the entity via PUT /entities/item/{entity_id}?
One suggested solution is to make the if-match header required instead of optional.