code: public void cleanup() {
          if (this.childStorages != null) {
              for (FileTempStorage storage : this.childStorages) {
                  storage.cleanup();
              }
          }
  
          for (File file : this.files.values()) {
              FileUtils.deleteQuietly(file);
          }
          this.files.clear();
      }
docs: Removes all temporary files from disk.
  IMPORTANT! Use this call only in the end
  when you are sure you don't need report files anymore