Refactor channel converter to support device configuration during discovery

[cdjackson]

This refactors the converters to allow the initialisation to be performed during discovery while devices are awake. This is necessary as channel discovery at a later time (ie once the thing is created) may fail for sleepy devices if the period between discovery and the thing creation is more than a few seconds (which is highly likely!).

In itself, this works, however as OH provides no way to parse the dynamic channels from the discovery handler to the new thing, when the thing handler is created the binding will again perform the channel discovery. For devices that are sleeping, this will fail - possibly this is ok, although it will likely indicate that the initialisation fails which may increase polling. In any case, the reporting should have been configured during discovery, so this should be working fine.

Ultimately to fully resolve this, the full discovery, including the static thing definition, all needs to be performed during discovery, and then there needs to be a way to parse this information to the thing handler.

This could be done using json encoded properties. Ideally OH would provide the ability to pass channel information to the DiscoveryResultBuilder (but it seems unlikely that OH would want to add this!).

Alternatively we could look to provide this support in the device storage - needs more thought, but this PR provides an initial intermediate step.

Adds partial support for #527.

Signed-off-by: Chris Jackson chris@cd-jackson.com

[openhab-bot]

This pull request has been mentioned on openHAB Community. There might be relevant details there:

https://community.openhab.org/t/zigbee-discovery-updates/109449/1