docs: private synchronized static void initialize() {
      if(MASTER_CACHE != null) {
        return;
      }
      try {
        Enumeration<URL> cps = CLASSLOADER.getResources("");
        List<Class<?>> res = new ArrayList<>();
        while(cps.hasMoreElements()) {
          URL u = cps.nextElement();
          // Scan file sources only.
          if(!"file".equals(u.getProtocol())) {
            continue;
          }
          try {
            Iterator<String> it = new DirClassIterator(new File(u.toURI()));
            while(it.hasNext()) {
              try {
                Class<?> cls = CLASSLOADER.loadClass(it.next());
                // skip classes where we can't get a full name.
                if(cls.getCanonicalName() == null) {
                  continue;
                }
                res.add(cls);
              }
              catch(Exception | Error e) {
                continue;
              }
            }
          }
          catch(URISyntaxException e) {
            LOG.warning("Incorrect classpath entry: " + u);
            continue;
          }
        }
        MASTER_CACHE = Collections.unmodifiableList(res);
        if(LOG.isDebuggingFinest()) {
          LOG.debugFinest("Classes found by scanning the development classpath: " + MASTER_CACHE.size());
        }
      }
      catch(IOException e) {
        LOG.exception(e);
        return;
      }
    }