Like the RouteDirectives the FileAndResourceDirectivesFileAndResourceDirectives are somewhat special in akka-http’s routing DSL. Most other directives wrap an inner route and are therefore used as inner nodes of the route tree. These directives, instead, are indeed instance of RouteRoute, i.e. leaves of the route tree that handle a request themselves without passing it on to an inner route.

So in most cases the inner-most element of a route structure branch is one of the RouteDirectives or FileAndResourceDirectivesFileAndResourceDirectives.

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