Adding a Message property to ILoggerStructure

If the structure returns no values, it means that it hasn't been initialized, or there is nothing in the collection of structures. For example, in MVC, in my action model I have a list of action constraints, each of which are ILoggerStructures. However, if the action model doesn't have any action constraints, that list will be empty. I still think it's important to have a message, because the property name is shown.