public override void Execute(object parameter)
{
    if (parameter == null)
    {
        return;
    }
    var context = (LoadOnDemandContext)parameter;
    context.ShowLoadOnDemandLoadingIndicator();

    var viewModel = this.Owner.BindingContext as LoadOnDemandViewModel;
    if (viewModel != null)
    {
        for (int i = 0; i < 10; i++)
        {
            viewModel.Items.Add(new Person { Name = "Person " + i, Age = i + 18, Address = "NEW Address" + i, Checked = false });
        }
    }
    Device.BeginInvokeOnMainThread(() => {
        context.HideLoadOnDemandLoadingIndicator();
    });
}