@Test
  void bodyWithTemplate() throws Exception {
    final MethodMetadata md =
        parseAndValidateMetadata(
            FormParams.class, "login", String.class, String.class, String.class);

    assertThat(md.template())
        .hasBodyTemplate(
            "%7B\"customer_name\": \"{customer_name}\", \"user_name\": \"{user_name}\","
                + " \"password\": \"{password}\"%7D");
  }
Tests interfaces defined per {@link Contract.Default} are interpreted into expected {@link feign
.RequestTemplate template} instances.
core/src/test/java/feign/DefaultContractTest.java