Values:
STATE_UNSPECIFIED (0):
Default value. This value is unused.
PENDING (1):
The PENDING state indicates that a Channel
has been created successfully and there is a new
activation token available for the subscriber to
use to convey the Channel to the provider in
order to create a Connection.
ACTIVE (2):
The ACTIVE state indicates that a Channel has
been successfully connected with the event
provider. An ACTIVE Channel is ready to receive
and route events from the event provider.
INACTIVE (3):
The INACTIVE state indicates that the Channel
cannot receive events permanently. There are two
possible cases this state can happen:
1. The SaaS provider disconnected from this
Channel.
2. The Channel activation token has expired but
the SaaS provider wasn't connected.
To re-establish a Connection with a provider,
the subscriber should create a new Channel and
give it to the provider.
