Can Anyone Explain the work flow of IExceptionHandler with Sample Client Application

I am facing below issues in this Sample: I am not able to find `IsOutermostCatchBlock` in `ExceptionContext` If Exception occurs, this `HandleAsync` method is executing twice. (http://www.asp.net/web-api/overview/web-api-routing-and-actions/web-api-global-error-handling) ``` public class CustomExceptionHandler : IExceptionHandler { public virtual Task HandleAsync(ExceptionHandlerContext context, CancellationToken cancellationToken) { if (!ShouldHandle(context)) { return Task.FromResult(0); } return HandleAsyncCore(context, cancellationToken); } public virtual Task HandleAsyncCore(ExceptionHandlerContext context, CancellationToken cancellationToken) { HandleCore(context); return Task.FromResult(0); } public virtual void HandleCore(ExceptionHandlerContext context) { } public virtual bool ShouldHandle(ExceptionHandlerContext context) { return context.ExceptionContext.IsOutermostCatchBlock; } } public class OopsExceptionHandler : CustomExceptionHandler { public override void HandleCore(ExceptionHandlerContext context) { context.Result = new TextPlainErrorResult { Request = context.ExceptionContext.Request, Content = "Oops! Sorry! Something went wrong." + "Please contact support@contoso.com so we can try to fix it." }; } private class TextPlainErrorResult : IHttpActionResult { public HttpRequestMessage Request { get; set; } public string Content { get; set; } public Task<HttpResponseMessage> ExecuteAsync(CancellationToken cancellationToken) { HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.InternalServerError); response.Content = new StringContent(Content); response.RequestMessage = Request; return Task.FromResult(response); } } } } ```