code: public List<String> getFiles(GerritQueryHandler gerritQueryHandler) {
          if (files == null) {
              files = FileHelper.getFilesByChange(gerritQueryHandler, id);
          }
          return files;
      }
docs: Queries gerrit for the files included in this patch set.
  
  @param gerritQueryHandler the query handler, responsible for the queries to gerrit.
  @return a list of files that are part of this patch set.