private LdapContextSource getLdapContextSource() throws Exception {
   LdapContextSource ldapContextSource = new DefaultSpringSecurityContextSource(ldapURL);
   ldapContextSource.setUserDn(ldapBindDN);
   ldapContextSource.setPassword(ldapBindPassword);
   ldapContextSource.setReferral(ldapReferral);
   ldapContextSource.setCacheEnvironmentProperties(false);
   ldapContextSource.setAnonymousReadOnly(false);
   ldapContextSource.setPooled(true);
   ldapContextSource.afterPropertiesSet();
   return ldapContextSource;
 }