protected Set<LdapGroupDto> getExternalLdapGroupInfo() {
    LdapServerProperties ldapServerProperties = getLdapProperties();
    EqualsFilter groupObjectFilter = new EqualsFilter(OBJECT_CLASS_ATTRIBUTE,
        ldapServerProperties.getGroupObjectClass());
    return getFilteredLdapGroups(ldapServerProperties.getBaseDN(), groupObjectFilter);
  }
Retrieves groups from external LDAP server.

@return set of info about LDAP groups
ambari-server/src/main/java/org/apache/ambari/server/security/ldap/AmbariLdapDataPopulator.java