Phillip Webb

Deprecate RootUriTemplateHandler in favor of DefaultUriBuilderFactory

2

`RootUriTemplateHandler` was added in Spring Boot 1.4 before `DefaultUriBuilderFactory` existed. The logic to prepend a root URL now duplicates what `DefaultUriBuilderFactory#initUriComponentsBuilder` is capable of doing by merging two parsed `UriComponent`...

See #35019 for the original feature. It's a bit clunky to use in Kotlin and I wonder if a helper is needed.