Avalonia search controltheme

<Window.Resources>
    <ControlTheme x:Key="int" TargetType="DataGridCell" BasedOn="{StaticResource {x:Type DataGridCell}}">
        <Setter Property="HorizontalAlignment" Value="Right" />
    </ControlTheme>
    <ControlTheme x:Key="str" TargetType="DataGridCell" BasedOn="{StaticResource {x:Type DataGridCell}}">
        <Setter Property="HorizontalAlignment" Value="Left" />
    </ControlTheme>
</Window.Resources>

var controlTheme = this.Find<ControlTheme>("x:Key=int");
var controlTheme = this.Find<ControlTheme>("int");....

var eng = new DataGridTextColumn();
eng.CellTheme = this.Find<ControlTheme>("int");