WCF known types gotcha

KnownType: if you use this at the base class level everything will work as expected

ServiceKnownType : one of the issue with serviceknowntype is that if you decorate it at the service implementation level(class) or the method implementation, it does not have any effect, the compiler does not throw any error, but during runtime the client call will fail(underlying connect closed), the solution is to always use the ServiceKnownType attribute on the service interface or the method in the interface.