protected override void CacheMetadata(ActivityMetadata metadata) { metadata.AddImportedChild(this.Left); metadata.AddImportedChild(this.Right); if (this.Left == null) { metadata.AddValidationError(System.Activities.SR.BinaryExpressionActivityRequiresArgument("Left", "OrElse", base.DisplayName)); } if (this.Right == null) { metadata.AddValidationError(System.Activities.SR.BinaryExpressionActivityRequiresArgument("Right", "OrElse", base.DisplayName)); } }