https://docs.spring.io/spring-framework/docs/6.2.15/javadoc-api/org/springframework/web/client/RestClient.RequestHeadersSpec.RequiredValueExchangeFunction.html
RestClient.RequestHeadersSpec.RequiredValueExchangeFunction (Spring Framework 6.2.15 API)
declaration: package: org.springframework.web.client, interface: RestClient, interface: RequestHeadersSpec, interface: RequiredValueExchangeFunction
spring frameworkrestclientapi