Implement MQTT5 enhancements

[bschaer]

We are using extensively the new MQTT5 features, namely properties. It would be nice if full (or at least partial) support for MQTT5 could be added. Most importantly we miss the following features:

• Display all property values coming with an incoming publish
• Being able to set at least the follownig properties with an outgoing publish:
  • Content Type
  • Response Topic
  • Correlation Data
  • User Property

[couling]

For me, just being able to connect with MQTT 5 protocol would be an advantage.

[friesendrywall]

Any update on this request?

[friesendrywall]

If you run from yarn, update package.json to use newest mqtt, then set like this in
backend/src/DataSource/MqttSource.ts

const client = mqttConnect(url, {
      resubscribe: false,
      rejectUnauthorized: options.certValidation,
      username: options.username,
      password: options.password,
      clientId: options.clientId,
      servername: options.tls ? url.hostname : undefined,
      ca: options.certificateAuthority ? Buffer.from(options.certificateAuthority, 'base64') : undefined,
      cert: options.clientCertificate ? Buffer.from(options.clientCertificate, 'base64') : undefined,
      key: options.clientKey ? Buffer.from(options.clientKey, 'base64') : undefined,
      protocolVersion: 5,
    } as any)

[bschaer]

Just to be able to connect to an MQTT5 broker is no benefit, if we cannot exploit the new MQTT5 features.

[friesendrywall]

Its of slight benefit to me, and @couling, however yes, I would prefer full features. Its a freeby though. I do find the tree representation of data nice vs the only other 5.0 compatible client mqqtx.