code: @Override
      public void clear() {
          try {
              warnUnusedOptions();
  
              if (clean == null || clean.getValue() == Boolean.TRUE) {
                  for (ExamSystem sys : subsystems) {
                      sys.clear();
                  }
                  FileUtils.delete(cache.getCanonicalFile());
              }
          }
          catch (IOException e) {
              // LOG.info("Clearing " + this.toString() + " failed." ,e);
          }
      }
docs: Clears up resources taken by system (like temporary files).