https://learn.microsoft.com/en-us/dotnet/api/system.web.mvc.nonactionattribute.isvalidforrequest?view=aspnet-mvc-5.2
NonActionAttribute.IsValidForRequest(ControllerContext, MethodInfo) Method (System.Web.Mvc) |...
Determines whether the attribute marks a method that is not an action method by using the specified controller context.
system webmethodmvc