**Testing pinging of the device and its online status:**
Monitoring the value of the `isOnline` field in the `tunnelbroker-device-sessions ` database table.
- Connecting to the bidirectional stream with the valid `sessionID` in metadata results in the value changing to `true` right after connection.
- Disconnecting from the stream or closing the client, resulting in the value becoming `false` in the `tunnelbroker-device-sessions database table in no more than 3 seconds (pinging interval).