@Test
  void headerParamsParseIntoIndexToName() throws Exception {
    final MethodMetadata md = parseAndValidateMetadata(headerParamsClass(), "logout", String.class);

    assertThat(md.template()).hasHeaders(entry("Auth-Token", asList("{Auth-Token}")));

    assertThat(md.indexToName()).containsExactly(entry(0, asList("Auth-Token")));
  }
Body type is only for the body param.
jaxrs/src/test/java/feign/jaxrs/JAXRSContractTestSupport.java