A brainstorming based on #29011 and further refinements in https://github.com/spring-projects/spring-framework/commit/bc0bf1fac3b2908ec4a488761f7b8cd8ad52f97a made it apparent that additional harmonization is needed.
Rather than registering a method or constructor, inferring a "default" ExecutableMode we need to make that mandatory so that it is explicit. When doing so, it turns out that the variant that takes a customizer of the builder isn't relevant at the moment as this is the only thing we can configure.
Similar harmonization is also required in TypeHint.