private static SamlPortConfigBuilder copyOf(SamlPortConfigBuilder that) {
        final SamlPortConfigBuilder builder = new SamlPortConfigBuilder();
        if (that.scheme != null) {
            builder.scheme = that.scheme;
        }
        if (isValidPort(that.port)) {
            builder.port = that.port;
        }
        return builder;
    }
Converts this builder to a {@link SamlPortConfigAutoFiller} in order to fill unspecified values
after the server started.
saml/src/main/java/com/linecorp/armeria/server/saml/SamlPortConfigBuilder.java