class S3ResourceId implements ResourceId {

  static S3ResourceId fromComponents(String bucket, String key) {
    if (!key.startsWith("/")) {
      key = "/" + key;
    }
    return new S3ResourceId(bucket, key, null, null);
  }

  private  S3ResourceId(
      String bucket, String key, @Nullable Long size, @Nullable Date lastModified);

}