Publish with Quality of Service (QoS) 2 to MQTT bridge is not supported in Google Cloud Platform (GCP)

When devices publish to MQTT bridge in GCP, they can set the Quality of Service to 0 or 1.

• When QoS is set to 0, the message will be delivered at most once.
• When QoS is set to 1, the message will be delivered at least once.
• When QoS is set to 2, the message will be delivered exactly once

However QoS 2 is not supported in the Google Cloud platform.

IoT Cloud Tester  application provides an easy interface to set the QoS for the MQTT connection.

• Publish with QoS 1
• Publish with QoS 0

To set Quality of Service (QoS) to 2 for MQTT connection and observe the failure,

• In the 'Publish' tab, select the value for the QoS field from the dropdown.
• Click on the 'Publish' button to start publishing data for the selected device(s).

When QoS is set to 2, the publish message will fail.