@Test
  void multipleInheritanceDoneWrong() {
    Throwable exception =
        assertThrows(
            IllegalStateException.class,
            () -> contract.parseAndValidateMetadata(MultipleInheritanceDoneWrong.class));
    assertThat(exception.getMessage())
        .contains("Only single inheritance supported: MultipleInheritanceDoneWrong");
  }
Tests interface inheritance defined per {@link Contract.Default} are interpreted into expected
{@link feign .RequestTemplate template} instances.
core/src/test/java/feign/DefaultContractInheritanceTest.java