Earlier, we saw a screenshot from Chrome's debug tools, showing request and response headers. There is another tool we can use as well--Spring Boot Actuator's trace endpoint.
By visiting http://localhost:8080/application/trace, we can see all the web calls, going back in time. For example, look at this request to negotiate the WebSocket:
{ "timestamp": 1480805242289, "info": { "method": "GET", "path": "/learning-spring-boot/160/ge00bkmu/websocket", "headers": { "request": { "host": "localhost:8080", "connection": "Upgrade", "pragma": "no-cache", "cache-control": "no-cache", "authorization": "Basic Z3JlZzp0dXJucXVpc3Q=", "upgrade": "websocket", "origin": "http://localhost:8080", "sec-websocket-version": "13", "user-agent": "Mozilla/5.0 ...
