Verifies the connection state

NOTE: This does not resubscribe to any channels it only returns the list of channels that the client should re-subscribe to.

Returns

Returns a list of `PushSubscriptionChanged` indicating the channels the consumer the client should re-subscribe to. If the list is empty, the client's connection was verified successfully, and the client does not need to resubscribe

Errors

Return an error in the following cases:

• The PushManager does not contain a valid UAID

• An error occurred sending an channel list retrieval request to the autopush server

• An error occurred accessing the PushManager's persisted storage