docs: @Nullable
      @Override
      protected AuthenticationInfo queryForAuthenticationInfo(
              AuthenticationToken token, LdapContextFactory ldapContextFactory) throws NamingException {
          try {
              return queryForAuthenticationInfo0(token, ldapContextFactory);
          } catch (ServiceUnavailableException e) {
              // It might be a temporary failure, so try again.
              return queryForAuthenticationInfo0(token, ldapContextFactory);
          }
      }