RestAPI: Content-Type header should not be required for GET

Using the v6.0 RestAPI, and trying to GET data from Spira  in json-format, the API requires that the Content-Type header is set to application/json.

Clearly, it should be the Accept header that should be conveyed with the application/json value. 

Example: 

curl --user <username>:<password> -H "Accept: application/json" https://spiraservice.net/Services/v6_0/RestService.svc/projects/9/releases 
returns a 400 Bad request error

while:

curl --user <username>:<password> -H "Content-Type: application/json" https://spiraservice.net/Services/v6_0/RestService.svc/projects/9/releases 
returns a 200 OK with the requested data.

Why does it matter?

Trying to send a GET request with a Content body (required to set the content-header) using a .NET HttpClient, throws:

ProtocolViolationException {"Cannot send a content-body with this verb-type."}

Getting Microsoft to change this behavior is probably not possible, but the Spira API should correctly handle the Accept header instead of the Content-Type header here.