code: @Override
      public Set<Node> findGroups(final String cn) {
          QueryBuilder qb = new LdapQueryBuilder();
          if ("*".equals(cn)) {
              qb.append(LdapKeys.OBJECT_CLASS, groupObjectClass);
          } else {
              qb.append(LdapKeys.OBJECT_CLASS, groupObjectClass);
              qb.append(groupIdentifyer, cn + "*");
          }
          return findGroups(qb);
      }
docs: Returns several LDAP-Groups for a given search-String.
  
  @param cn the cn (or part of cn) for the groups.
  @return Groups as a Set of Nodes.