This commit declares each of the following public interfaces as a
@FunctionalInterface.
- org.springframework.context.ApplicationContextInitializer
- org.springframework.test.web.servlet.DispatcherServletCustomizer
- org.springframework.validation.MessageCodeFormatter
- org.springframework.util.IdGenerator
- org.springframework.beans.factory.config.YamlProcessor.MatchCallback
- org.springframework.beans.factory.config.YamlProcessor.DocumentMatcher
Closes gh-25580