Declare interfaces as @FunctionalInterface where feasible #25580
Description
As a follow up to #25571, in my opinion, the following are the remaining potential candidates for being annotated with @FunctionalInterface, especially the first two.
org.springframework.context.ApplicationContextInitializerorg.springframework.test.web.servlet.DispatcherServletCustomizerorg.springframework.validation.MessageCodeFormatterorg.springframework.util.IdGeneratororg.springframework.beans.factory.config.YamlProcessor.MatchCallbackorg.springframework.beans.factory.config.YamlProcessor.DocumentMatcher