docs: public void deleteFileName(final String fileName) {
        writeLock.lock();
        try {
           FileListCacheValue fileList = getFileList();
           boolean done = fileList.remove(fileName);
           if (done) {
              updateFileList(fileList);
              if (trace)
                 log.trace("Updated file listing: removed " + fileName);
           }
        } finally {
           writeLock.unlock();
        }
     }