AjaxControlToolkit.DynamicPopulateExtender.CheckIfValid C# (CSharp) Method

        protected override bool CheckIfValid(bool throwException)
        {
            if(String.IsNullOrEmpty(CustomScript) && String.IsNullOrEmpty(ServiceMethod)) {
                if(throwException)
                    throw new InvalidOperationException("CustomScript or ServiceMethod must be set.");
                return false;
            }
            return base.CheckIfValid(throwException);
        }