UI Toolkit disable button in uxml template

<ButtonThatCanBeDisabled text="Save" name="optionsSaveBut" class="button" enabled="false"/>

 // web* src: https://gist.github.com/andrew-raphael-lukasik/69c7858e39e22f197ca51b318b218cc7
 using UnityEngine.UIElements;
 
 [UnityEngine.Scripting.Preserve]
 public class ButtonThatCanBeDisabled : Button
 {
     public bool enabled {
         get => enabledSelf;
         set => SetEnabled(value);
     }
     public new class UxmlFactory : UxmlFactory<ButtonThatCanBeDisabled,UxmlTraits> {}
     public new class UxmlTraits : Button.UxmlTraits
     {
         UxmlBoolAttributeDescription enabledAttr = new UxmlBoolAttributeDescription{ name="enabled" , defaultValue=true };
         public override void Init ( VisualElement ve , IUxmlAttributes attributes , CreationContext context )
         {
             base.Init( ve , attributes , context );
             ButtonThatCanBeDisabled instance = (ButtonThatCanBeDisabled) ve;
             instance.enabled = enabledAttr.GetValueFromBag( attributes , context );
         }
     }
 }