code: public static <V, X extends Exception> CheckedFuture<V, X>
        immediateFailedCheckedFuture(X exception) {
      checkNotNull(exception);
      return new ImmediateFailedCheckedFuture<V, X>(exception);
    }
docs: Returns a {@code CheckedFuture} which has an exception set immediately upon
  construction.
  
  <p>The returned {@code Future} can't be cancelled, and its {@code isDone()}
  method always returns {@code true}. Calling {@code get()} will immediately
  throw the provided {@code Exception} wrapped in an {@code
  ExecutionException}, and calling {@code checkedGet()} will throw the
  provided exception itself.