@Override
    public void onFileDelete(FileDeletionEvent event) {
        if (diskPermits != null)
            diskPermits.release();
    }
Returns the file output stream to be used for writing, blocking if
necessary if running out of disk space.

@throws InterruptedException if the running thread was interrupted
aws-java-sdk-s3/src/main/java/com/amazonaws/services/s3/internal/MultiFileOutputStream.java