@Test
    void tlsCustomizationWithFile() {
        tlsCustomization(sb -> sb.tls(selfSignedCertificate.certificateFile(),
                                      selfSignedCertificate.privateKeyFile()),
                         vhb -> vhb.tls(selfSignedCertificate.certificateFile(),
                                        selfSignedCertificate.privateKeyFile()));
    }
Makes sure that {@link ServerBuilder#decorator(DecoratingHttpServiceFunction)} works at every service and
virtual hosts and {@link VirtualHostBuilder#decorator(DecoratingHttpServiceFunction)} works only at
its own services.
core/src/test/java/com/linecorp/armeria/server/ServerBuilderTest.java