D365O - Insert data in C# via entities - Exchange rates

Hello,

I am trying to use an external application to connect to D365 in C# to insert exchange rates via based on the Github file example :

https://github.com/Microsoft/Dynamics-AX-Integration

I am able to connect and use the sample queries.

I tried to create my own methods to insert exchange rates :

        public static void CreateExchangeRates(Resources d365)
        {
            ExchangeRate xRate;

            xRate = new ExchangeRate()
            {
                FromCurrency = "EUR",
                ToCurrency = "GBP",
                Rate = 0.9999M,
                RateTypeName = "Default",
                StartDate = new DateTime(2017, 11, 15),
                ConversionFactor = ODataUtility.Microsoft.Dynamics.DataEntities.ExchangeRateDisplayFactor.One
            };

            // Create
            d365.AddToExchangeRates(xRate);
            d365.SaveChanges();
            Console.WriteLine(string.Format("Done"));
        }

When I call this method, it refuses my insert because I am not allowed to set the value EndDate. Enddate is not allowed to be set as its handled by the system. How can i handle the "mapping" to not try to set the endDate? 

This is the error that i get :

Microsoft.OData.Client.DataServiceRequestException occurred
  HResult=0x80131509
  Message=An error occurred while processing this request.
  Source=Microsoft.OData.Client
  StackTrace:
   at Microsoft.OData.Client.SaveResult.HandleResponse()
   at Microsoft.OData.Client.BaseSaveResult.EndRequest()
   at Microsoft.OData.Client.DataServiceContext.SaveChanges(SaveChangesOptions options)
   at ODataConsoleApplication.QueryExamples.CreateExchangeRates(Resources d365) in C:\**********\Dynamics-AX-Integration-master\ServiceSamples\ODataConsoleApplication\QueryExamples.cs:line 45
   at ODataConsoleApplication.Program.Main(String[] args) in C:\***********\Dynamics-AX-Integration-master\ServiceSamples\ODataConsoleApplication\Program.cs:line 37

Inner Exception 1:
DataServiceClientException: {
  "error":{
    "code":"","message":"An error has occurred.","innererror":{
      "message":"insert not allowed for field 'EndDate'","type":"Microsoft.Dynamics.Platform.Integration.Services.OData.ODataSecurityException","stacktrace":"   at Microsoft.Dynamics.Platform.Integration.Services.OData.Update.UpdateProcessor.CreateEntity_Save(ChangeOperationContext context, ChangeInfo changeInfo)\r\n   at Microsoft.Dynamics.Platform.Integration.Services.OData.Update.UpdateManager.<>c__DisplayClass5_0.<CreateEntity>b__1(ChangeOperationContext context)\r\n   at Microsoft.Dynamics.Platform.Integration.Services.OData.Update.ChangeInfo.ExecuteActionsInCompanyContext(IEnumerable`1 actionList, ChangeOperationContext operationContext)\r\n   at Microsoft.Dynamics.Platform.Integration.Services.OData.Update.ChangeInfo.TrySave(ChangeOperationContext operationContext)\r\n   at Microsoft.Dynamics.Platform.Integration.Services.OData.Update.UpdateManager.SaveChanges()\r\n   at Microsoft.Dynamics.Platform.Integration.Services.OData.AxODataDelegatingHandler.<SaveChangesAsync>d__2.MoveNext()"
    }
  }
}

Thank you in advance for your kind help !