private static HealthCheckedEndpointGroup build(HealthCheckedEndpointGroupBuilder builder,
                                                    SessionProtocol protocol) {
        return builder.protocol(protocol)
                      .clientOptions(ClientOptions.builder()
                                                  .factory(ClientFactory.insecure())
                                                  .decorator(LoggingClient.newDecorator())
                                                  .build())
                      .build();
    }
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