clarification needed on expected usage of deviceGroup -> device

1. looking at the code and the docs it looks like that at creation time a deviceGroup is identified by the tuple (resource,apiKey). This means that under the same service,subservice there may be different deviceGroups.

2. it is then unclear, at provisioning time of a device provisioning time how the relation is created since, the only information passed is service,subservice, which seems to imply that device group can be only and only one for a tuple service,subservice.

3. the only moment were apikey is used is during the device update. which can imply that with a single deviceId registered and linked to a tuple service,subservice if 2 service groups with different apiKey are recorded, you would end up being able (for the same device) to register total different data (due to the two configuration of device group) but just using the two different apiKey.

not sure this is a feature or a bug :)

Start by tracing how deviceGroups are created and how device provisioning links a device using service and subservice. Compare that relation with the later apiKey-based device update path, then document the intended uniqueness and linkage rules, including whether multiple deviceGroups may exist for the same service and subservice.