Actual request may be manipulated after it has been logged

In my Spring enabled App I'm using Feign (spring-cloud-starter-feign) and Sleuth (spring-cloud-starter-sleuth).
Now I wanted to check whether in an HTTP request Sleuth's traceId is transferred in the HTTP headers. Thus I used Feign's Logger.Level.HEADERS. I could see headers being logged, but the trace information was missing - although it was actually being transferred.

From debugging I found out that logging takes place before Sleuth's tracing information is added to the headers, thus the information is misleading.
Here the succession of logging and request manipulation is defined: feign.SynchronousMethodHandler.executeAndDecode(RequestTemplate)
Here the manipulation of the request headers takes place: org.springframework.cloud.sleuth.instrument.web.client.feign.TraceFeignClient.execute(Request, Options)

I would expect that if I enable Logger.Level.HEADERS I see all the header information that is actually being sent.

Read Feign's SynchronousMethodHandler.executeAndDecode(RequestTemplate) alongside Spring Cloud Sleuth's TraceFeignClient.execute(Request, Options) to trace when logging and header manipulation occur. Reproduce the request with Logger.Level.HEADERS and Sleuth enabled; done means the logged headers match the headers actually sent, including the traceId.