static void FillStack(BlittableJsonReader reader, int numberOfItems) { var stackField = reader.GetType().BaseType.GetField("_stack", BindingFlags.Instance | BindingFlags.NonPublic); var stackFieldItem = stackField.FieldType.GetGenericArguments()[0]; var stack = (IList)stackField.GetValue(reader); while (stack.Count < numberOfItems) { var item = Activator.CreateInstance(stackFieldItem); var typeField = item.GetType().GetField("Type", BindingFlags.Instance | BindingFlags.NonPublic); typeField.SetValue(item, 1); // :) var propertyNameField = item.GetType().GetField("PropertyName", BindingFlags.Instance | BindingFlags.NonPublic); propertyNameField.SetValue(item, $"Field_{stack.Count}"); stack.Add(item); } }