Make GenericApplicationContext the default ApplicationContext class for non-webapp

[dsyer]

GenericApplicationContext is arguably a better choice these days and all the default webapp context types used by Boot are GenericApplicationContext, so it would make things (by default) uniform and more predictable. It would simplify the job of anyone trying to add ApplicationContextInitializers with functional bean definitions.

[philwebb]

The default is currently AnnotationConfigApplicationContext which extends GenericApplicationContext. This works:

SpringApplication application = new SpringApplication(ScratchApplication.class);
application.setWebApplicationType(WebApplicationType.NONE);
GenericApplicationContext run = (GenericApplicationContext) application.run(args);

Is AnnotationConfigApplicationContext doing too much or causing some other issues?

[dsyer]

I don't think it was always a GenericApplicationContext, was it (maybe I am misremembering)? Anyway it has a built in AnnotatedBeanDefinitionReader which is too much for anything that doesn't want to use @Configuration or wants to control it a bit more. Probably this can be rolled up into #8115.

[philwebb]

I've added a comment to #8115.