code: private void onCopyFailure(
        KeySetView<IOException, Boolean> innerExceptions,
        GoogleJsonError e,
        String srcBucketName, String srcObjectName) {
      if (errorExtractor.itemNotFound(e)) {
        FileNotFoundException fnfe =
            GoogleCloudStorageExceptions.getFileNotFoundException(srcBucketName, srcObjectName);
        innerExceptions.add((FileNotFoundException) fnfe.initCause(new IOException(e.toString())));
      } else {
        String srcString = StorageResourceId.createReadableString(srcBucketName, srcObjectName);
        innerExceptions.add(new IOException(String.format("Error copying %s:%n%s", srcString, e)));
      }
    }
docs: Processes failed copy requests