docs: protected static synchronized void initCache() {
          if (m_Cache == null) {
              m_Cache = new ClassCache();
              // failed to locate any classes on the classpath, maybe inside Weka?
              // try loading fixed list of classes
              if (m_Cache.isEmpty()) {
                  InputStream inputStream = null;
                  try {
                      inputStream = m_Cache.getClass().getResourceAsStream(CLASS_LIST);
                      m_Cache = new ClassCache(new FixedClassListTraversal(inputStream));
                  }
                  catch (Exception e) {
                      System.err.println("Failed to initialize class cache from fixed list (" + CLASS_LIST + ")!");
                      e.printStackTrace();
                  }
                  finally {
                      if (inputStream != null) {
                          try {
                              inputStream.close();
                          }
                          catch (Exception e) {
                              // ignored
                          }
                      }
                  }
              }
          }
      }