code: @Transactional(readOnly = false, propagation = Propagation.REQUIRES_NEW,
      isolation = Isolation.READ_COMMITTED)
    public void checkAndRemoveTopLevelCorpus(String corpusName)
    {
      if (existConflictingTopLevelCorpus(corpusName))
      {
        log.info("delete conflicting corpus: {}", corpusName);
        List<String> corpusNames = new LinkedList<>();
        corpusNames.add(corpusName);
        deleteCorpora(getQueryDao().mapCorpusNamesToIds(corpusNames), false);
      }
    }
docs: Deletes a top level corpus, when it is already exists.
  @param corpusName