generateChannelIdIfNeeded
Generates the channel id based on the member ids if provided channelId is empty. Member-based id should only be used for creating distinct channels. Created member-based id might differ from the one created by the server if the channel already exists and was created with different members order.
Return
channelId if not blank or new, member-based id.
Parameters
channelId
The channel id. ie 123.
memberIds
The list of members' ids.