@Test
public void getDefaultHttpStatusCodeCircuitBreakerForKey_methods_convert_null_key_to_blank_string() {

    // given
    Optional<ScheduledExecutorService> scheduler = Optional.of(mock(ScheduledExecutorService.class));
    Optional<ExecutorService> scne = Optional.of(mock(ExecutorService.class));
    // when
    CircuitBreaker<Integer> nullKeyDefaultMethodResult =
        CircuitBreakerForHttpStatusCode.getDefaultHttpStatusCodeCircuitBreakerForKey(null);
    CircuitBreaker<Integer> emptyKeyDefaultMethodResult =
        CircuitBreakerForHttpStatusCode.getDefaultHttpStatusCodeCircuitBreakerForKey("");
    CircuitBreaker<Integer> nullKeyCustomMethodResult =
        CircuitBreakerForHttpStatusCode.getDefaultHttpStatusCodeCircuitBreakerForKey(null, scheduler, scne);
    CircuitBreaker<Integer> emptyKeyCustomMethodResult =
        CircuitBreakerForHttpStatusCode.getDefaultHttpStatusCodeCircuitBreakerForKey("", scheduler, scne);
    // then
    assertThat(emptyKeyDefaultMethodResult).isSameAs(nullKeyDefaultMethodResult);
    assertThat(nullKeyCustomMethodResult).isSameAs(nullKeyDefaultMethodResult);
    assertThat(emptyKeyCustomMethodResult).isSameAs(nullKeyDefaultMethodResult);
}