public interface IEntityTyped
{
    [Association(OnTargetRemove = OnRemoveAction.Cascade)]
    [Field(Nullable = false)]
    string ItemType { get; set; }
}

[Serializable]
[HierarchyRoot]
public class FakeEntity : Entity, IEntityTyped
{
    [Field]
    public string Idqwe { get; private set; }

    [Association(OnTargetRemove = OnRemoveAction.Default)]
    public string ItemType { get; set; }
}

Just create this setup, it will fail during compile-time