SpringBoot restTemplateBuilderConfigurer doesn't need to be @ConditionalOnMissingBean

restTemplateBuilderConfigurer defined by RestTemplateAutoConfiguration is @ConditonalOnMissingBean but that condition doesn't appear to be necessary. RestTemplateBuilderConfigurer is a final class and is immutable from the perspective of its public API. You could define a custom configurer bean but it would be in its default state and would do nothing when asked to configure the RestTemplateBuilder. You could just define a RestTemplateBuilder bean directly instead:

@Bean
public RestTemplateBuilder restTemplateBuilder() {
     return new RestTemplateBuilder();
}

We should remove @ConditonalOnMissingBean. In the unlikely event of someone having defined their own RestTemplateBuilderConfigurer this would be a breaking change as two RestTemplateBuilderConfigurer beans would then be defined. As such, we should remove the condition in 3.2 at the earliest and mention the change in the release notes.

Comment From: wilkinsona

Closing in favor of https://github.com/spring-projects/spring-boot/pull/37746.