@Test
  void resolveTemplateWithBodyTemplateSetsBodyAndContentLength() {
    RequestTemplate template =
        new RequestTemplate()
            .method(HttpMethod.POST)
            .bodyTemplate(
                """
                %7B"customer_name": "{customer_name}", "user_name": "{user_name}", \
                "password": "{password}"%7D\
                """,
                Util.UTF_8);

    template =
        template.resolve(
            mapOf("customer_name", "netflix", "user_name", "denominator", "password", "password"));

    assertThat(template)
        .hasBody(
            "{\"customer_name\": \"netflix\", \"user_name\": \"denominator\", \"password\":"
                + " \"password\"}")
        .hasHeaders(
            entry(
                "Content-Length",
                Collections.singletonList(String.valueOf(template.body().length))));
  }
This ensures we don't mess up vnd types
core/src/test/java/feign/RequestTemplateTest.java