The OP/GP wasn't really complaining about inheritance, despite the fact that this is what they wrote. The OP is complaining about the difficulty of the API bec

The OP/GP wasn't really complaining about inheritance, despite the fact that this is what they wrote. The OP is complaining about the difficulty of the API because it is _exposed_ through inheritance. The complaint about `SpringBootServletInitializer`, for example, is exactly this. There's nothing wrong with inheritance. In fact, SpringBootServletInitializer is exactly what you want to use inheritance for - because you need to build your app using the servlet api. There are http servers that aren't servlet api, such as https://vertx.io/docs/vertx-web/java/#_re_cap_on_vert_x_core_http_servers https://vertx.io/docs/vertx-web/java/#_re_cap_on_vert_x_core... , which uses little to no inheritance (since the api surface is smaller).