@Test
  void formParamAndBodyParams() throws Exception {
    Throwable exception =
        assertThrows(
            IllegalStateException.class,
            () ->
                parseAndValidateMetadata(
                    FormParams.class, "formParamAndBodyParams", String.class, String.class));
    assertThat(exception.getMessage())
        .contains("Body parameters cannot be used with form parameters.");
  }
Tests interfaces defined per {@link Contract.Default} are interpreted into expected {@link feign
.RequestTemplate template} instances.
core/src/test/java/feign/DefaultContractTest.java