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

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

    assertThat(md.indexToName()).containsExactly(entry(0, asList("authToken")));
    assertThat(md.formParams()).isEmpty();
  }
Body type is only for the body param.
core/src/test/java/feign/DefaultContractTest.java