Reading https://docs.spring.io/spring-framework/docs/current/reference/html/testing.html#spring-mvc-test-server-performing-requests it is not obvious where post(...) and the like methods start from. With the apache http-client on my classpath my IDE wants to suggest that they come from that RequestBuilder. I did ultimately find an example with the location on the javadoc, of course the MockMvc javadoc, which is not where I'd have looked for this.
Comment From: rstoyanchev
Note that we have a section on that https://docs.spring.io/spring-framework/docs/current/reference/html/testing.html#spring-mvc-test-server-static-imports but I can insert more links to that from a few places.