@Test
    void initialHealthCheckCanHaveEndpoints() throws Exception {
        serverOne.start();

        // even localhost usually takes long enough to resolve that this test would never work if the initial
        // health check didn't wait for localhost's DNS resolution.
        final int port = serverOne.httpPort();
        try (HealthCheckedEndpointGroup endpointGroup =
                     HealthCheckedEndpointGroup.builder(DnsAddressEndpointGroup.of("localhost", port),
                                                        HEALTH_CHECK_PATH)
                                               .retryInterval(Duration.ofHours(1))
                                               .withClientOptions(b -> {
                                                   return b.decorator(LoggingClient.newDecorator());
                                               })
                                               .build()) {

            assertThat(endpointGroup.whenReady().get(10, TimeUnit.SECONDS)).hasSize(1);
        }
    }
When an endpoint has an IP address already, the health checker must send a health check request using
an IP address, because otherwise the health checker can send the health check request to a wrong host
if there are more than one IP addresses assigned to the host name.
core/src/test/java/com/linecorp/armeria/client/endpoint/healthcheck/HealthCheckedEndpointGroupIntegrationTest.java