@Test
  void errorMessageOnMixedContracts() {
    Throwable exception =
        assertThrows(
            IllegalStateException.class,
            () -> contract.parseAndValidateMetadata(MixedAnnotations.class));
    assertThat(exception.getMessage()).contains("are not used by contract Default");
  }
Let's help folks not lose time when they mistake request line for a URI!
core/src/test/java/feign/DefaultContractTest.java