4.1.2 updates the SDK to pass the access token in the headers instead of in the URL. For websocket connections this means the access token is now passed in the Sec-WebSocket-Protocol header.
Node.js Usage with Cloud Configuration
If you are using node.js with Cloud configuration and are providing a webSocketFactoryFunction in your device connection configuration you will need to update your function to create a websocket that passes the access token in the Sec-WebSocket-Protocol header. An example can be found here and here.
If you want to use the https://www.npmjs.com/package/ws implementation, you can create a global variable in your code like global.WebSocket = require('ws') and then you are not required to use the webSocketFactoryFunction parameter.
Browser Based
If you have a browser based implementation you likely won't need to change anything.