Missing check of presence of "WWW-Authenticate HTTP header" when "401 Unauthorized" error code is received
401 Unauthorized: If the request contains no access token even though one is required, or if the request contains an authorization token that is invalid (e.g. expired or revoked), the API producer should respond with this response. The details of the error shall be returned in the WWW-Authenticate HTTP header, as defined in IETF RFC 6750  and IETF RFC 7235 . The ProblemDetails structure may be provided.