@Test
  void templateWithTemplateExpressionLiteralHeader() {
    String header = "{var}";
    RequestTemplate template =
        new RequestTemplate().method(HttpMethod.GET).headerLiteral("A-Header", header);

    template = template.resolve(mapOf("var", "value"));
    assertThat(template).hasHeaders(entry("A-Header", Collections.singletonList(header)));
  }
This ensures we don't mess up vnd types
core/src/test/java/feign/RequestTemplateTest.java