public SamlServiceProviderBuilder metadataPath(String metadataPath) {
        this.metadataPath = requireNonNull(metadataPath, "metadataPath");
        return this;
    }
Sets a URL for retrieving a metadata of this service provider.
saml/src/main/java/com/linecorp/armeria/server/saml/SamlServiceProviderBuilder.java