private async Task <OAuthSession> JWTAuthPostAsync(string assertion)
{
BoxRequest boxRequest = new BoxRequest(_boxConfig.BoxApiHostUri, Constants.AuthTokenEndpointString)
.Method(RequestMethod.Post)
.Header(Constants.RequestParameters.UserAgent, _boxConfig.UserAgent)
.Payload(Constants.RequestParameters.GrantType, Constants.RequestParameters.JWTAuthorizationCode)
.Payload(Constants.RequestParameters.Assertion, assertion)
.Payload(Constants.RequestParameters.ClientId, _boxConfig.ClientId)
.Payload(Constants.RequestParameters.ClientSecret, _boxConfig.ClientSecret);
var converter = new BoxJsonConverter();
IBoxResponse <OAuthSession> boxResponse = await _boxService.ToResponseAsyncWithoutRetry <OAuthSession>(boxRequest).ConfigureAwait(false);
boxResponse.ParseResults(converter);
return(boxResponse.ResponseObject);
}