public RoutingTableSpec setRoute(int i, RouteSpec route) {
        routes.set(i, route);
        return this;
    }
Sets the route spec at the given index.

@param i     The index at which to set the route.
@param route The route to set.
@return This, to allow chaining.
messagebus/src/main/java/com/yahoo/messagebus/routing/RoutingTableSpec.java