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

    template.resolve(new LinkedHashMap<>());
    assertThat(template).hasHeaders(entry("A-Header", Collections.singletonList(emptyJsonObject)));
  }
This ensures we don't mess up vnd types
core/src/test/java/feign/RequestTemplateTest.java