channels
A collection of Sync Gateway channel names from which to pull Documents. If unset, all accessible channels will be pulled. Default is empty: pull from all accessible channels.
Note: Channel specifications apply only to replications pulling from a SyncGateway and only the channels visible to the authenticated user. Channel specs are ignored:
during a push replication.
during peer-to-peer or database-to-database replication
when the specified channel is not accessible to the user