docs: public synchronized void cleanup() {
          for (Enumeration e = jarFiles.elements(); e.hasMoreElements();) {
              JarFile jarFile = (JarFile) e.nextElement();
              try {
                  jarFile.close();
              } catch (IOException ioe) {
                  // ignore
              }
          }
          jarFiles = new Hashtable();
          if (project != null) {
              project.removeBuildListener(this);
          }
          project = null;
      }