What is the purpose of HttpRequestMessage.Properties?
I'm wondering if it provides something useful for my application.
In Web Api it contains some special flags: http://www.strathweb.com/2013/08/asp-net-web-api-2-and-httprequestcontext/
For example, IncludeErrorDetail, IsLocal, ClientCertificate are stored in the dictionary, but have properties for easy access.