REST operations are always sent with application/fhir+xml headers

[SharonHart]

When POSTing or PUTing a resource, the tool logs that the request is sent with json-based Accept and Content-Type, but the actual headers value is application/fhir+xml
Also setting the headers implicitly with fhir server header to application/fhir+json doesn't help.
As some FHIR implementations are restricting the value to application/fhir+json, the tool is not working agains them.

From Fiddler profiling:

Key: Host; Value: localhost:8080
Key: User-Agent; Value: .NET FhirClient for FHIR 4.0.1
Key: Accept; Value: application/fhir+xml; charset=utf-8; fhirVersion=4.0
Key: Accept-Encoding; Value: gzip, deflate
Key: Content-Type; Value: application/fhir+xml; charset=utf-8; fhirVersion=4.0
Key: Content-Length; Value: 9356