[Feature Request] Do not log a stack trace at WARN level when an MQTT connection is lost

[gabrielandrade2]

Context

• OS and version used: Ubuntu 26.04
• Java runtime used: OpenJDK version "17.0.19" 2026-04-21
• SDK version used: 2.5.1
• Protocol used: MQTT over WebSockets

Whenever an MQTT connection is lost, the SDK changes the transport status to DISCONNECTED_RETRYING with reason NO_NETWORK and logs the event at WARN level.

The warning includes the complete stack trace of the associated ProtocolException. This happens every time the MQTT connection is lost.

When a device experiences frequent connection interruptions, the same stack trace is logged repeatedly. This can generate a large volume of logs in a short period, even though the SDK is handling the interruption through its normal reconnection mechanism.

For example, the following sequence is repeated for every disconnection:

2026-08-16T03:06:28,025 | INFO | <IOT_HUB_HOSTNAME>-<DEVICE_ID>-<CONNECTION_ID>-azure-iot-sdk-IotHubReconnectTask | IotHubTransport | <BUNDLE_ID> - <APPLICATION_NAME> - <APPLICATION_VERSION> | Updating transport status to new status CONNECTED with reason CONNECTION_OK

2026-08-16T03:06:29,546 | WARN | MQTT Rec: <DEVICE_ID> | IotHubTransport | <BUNDLE_ID> - <APPLICATION_NAME> - <APPLICATION_VERSION> | Updating transport status to new status DISCONNECTED_RETRYING with reason NO_NETWORK
com.microsoft.azure.sdk.iot.device.transport.ProtocolException: Mqtt connection lost
    at com.microsoft.azure.sdk.iot.device.transport.mqtt.exceptions.PahoExceptionTranslator.convertToMqttException(PahoExceptionTranslator.java:63)
    at com.microsoft.azure.sdk.iot.device.transport.mqtt.Mqtt.connectionLost(Mqtt.java:335)
    at org.eclipse.paho.client.mqttv3.internal.CommsCallback.connectionLost(CommsCallback.java:304)
    at org.eclipse.paho.client.mqttv3.internal.ClientComms.shutdownConnection(ClientComms.java:441)
    at org.eclipse.paho.client.mqttv3.internal.CommsReceiver.run(CommsReceiver.java:197)
    at java.lang.Thread.run(Unknown Source)
Caused by: org.eclipse.paho.client.mqttv3.MqttException: Connection lost
    ... 2 more
Caused by: java.io.EOFException
    at java.io.DataInputStream.readUnsignedByte(Unknown Source)
    at java.io.DataInputStream.readByte(Unknown Source)
    at org.eclipse.paho.client.mqttv3.internal.wire.MqttInputStream.readMqttWireMessage(MqttInputStream.java:92)
    at org.eclipse.paho.client.mqttv3.internal.CommsReceiver.run(CommsReceiver.java:137)
    ... 1 more

2026-08-16T03:06:29,734 | INFO | <IOT_HUB_HOSTNAME>-<DEVICE_ID>-<CONNECTION_ID>-azure-iot-sdk-IotHubReconnectTask | IotHubTransport | <BUNDLE_ID> - <APPLICATION_NAME> - <APPLICATION_VERSION> | Updating transport status to new status CONNECTED with reason CONNECTION_OK

I believe that the whole stacktrace would not be necessary here. Perhaps just the message of the exception and/or the message of the cause would suffice:

2026-08-16T03:06:29,546 | WARN | MQTT Rec: <DEVICE_ID> | IotHubTransport | <BUNDLE_ID> - <APPLICATION_NAME> - <APPLICATION_VERSION> | Updating transport status to new status DISCONNECTED_RETRYING with reason NO_NETWORK: Mqtt connection lost (cause: Connection lost)
2026-08-16T03:06:29,734 | INFO | <IOT_HUB_HOSTNAME>-<DEVICE_ID>-<CONNECTION_ID>-azure-iot-sdk-IotHubReconnectTask | IotHubTransport | <BUNDLE_ID> - <APPLICATION_NAME> - <APPLICATION_VERSION> | Updating transport status to new status CONNECTED with reason CONNECTION_OK

Thank you very much for your support.