iobject .net
            Datasource datasource = workspace1.Datasources[0];
            DatasetVectorInfo pointLayerInfo = new DatasetVectorInfo("point", DatasetType.Point);         
            DatasetVector pointDataset = datasource.Datasets.Create(pointLayerInfo);
            mapControl1.Map.Layers.Add(pointDataset,true);
System.InvalidOperationException:“不能修改只读对象”