C#

private void button1_Click(object sender, EventArgs e)
    {
    Button b = new Button();
    b.Text = $"Hello: {++buttonsCount}";
    b.Click += MyAddedButton_Click;
    myFlowLayoutPanel.Controls.Add(b);
    }
private int buttonsCount = 0;
private void MyAddedButton_Click(object sender, EventArgs e)
    {
    Console.WriteLine((sender as Button)?.Text);
    }

private void Btn_Add_Click(object sender, EventArgs e)
{
    var ucCount = panelItems.Controls.Count;
    var ucLocation = new Point(0, 0);

    var shipmentControl = new AmazonFBAShipmentControl(inventoryRepository);
    shipmentControl.Location = ucLocation;

    panelItems.Controls.Add(shipmentControl);

}

private string _info = null;
public string Info { get { return _info ?? "I'm empty"; } set { _info = value; } }

Quote:

AllowNull: A non-nullable input argument may be null.
DisallowNull: A nullable input argument should never be null.
MaybeNull: A non-nullable return value may be null.
NotNull: A nullable return value will never be null.
MaybeNullWhen: A non-nullable input argument may be null when the method returns the specified bool value.
NotNullWhen: A nullable input argument will not be null when the method returns the specified bool value.
NotNullIfNotNull: A return value isn't null if the argument for the specified parameter isn't null.
DoesNotReturn: A method never returns. In other words, it always throws an exception.
DoesNotReturnIf: This method never returns if the associated bool parameter has the specified value.