docs: @Override
    public String getDefaultManagerName(ClassLoader cl) {
      ConfigurationContext ctx = classLoader2config.get(cl);
      if (ctx == null) {
        ctx = createContext(cl, null, DEFAULT_CONFIGURATION_FILE);
        Map<ClassLoader, ConfigurationContext> m2 = new HashMap<ClassLoader, ConfigurationContext>(classLoader2config);
        m2.put(cl, ctx);
        classLoader2config = m2;
      }
      return ctx.getManagerConfiguration().getDefaultManagerName();
    }