@Override
      public ListenableFuture<V> apply(X t) {
        throw newAssertionError("Unexpected fallback", t);
      }
    };
  }

  /** Alternative to AssertionError(String, Throwable), which doesn't exist in GWT 2.6.1. */
  private static AssertionError newAssertionError(String message, Throwable cause) {
    AssertionError e = new AssertionError(message);
    e.initCause(cause);
    return e;
  }

    /** The key of the message: system.properties does not exist. Default values are applied. */
    public static final String LABELS_system_info_system_properties_does_not_exist =
            "{labels.system_info_system_properties_does_not_exist}";

    /** The key of the message: File Authentication */