class GcpSSHKeyMetadata {

    public static String metadataFormat (Collection<GcpSSHKeyMetadata> metadataCollection) {
        return metadataCollection.stream()
                                 .map(GcpSSHKeyMetadata::metadataFormat)
                                 .collect(Collectors.joining("\n", "", "\n"));
    }

      GcpSSHKeyMetadata(String username, String publicKey, String identifier);

}