@Override
    public String toString() {
        return MoreObjects.toStringHelper(this)
                          .add("scheme", scheme)
                          .add("port", port)
                          .toString();
    }
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