code: @SuppressWarnings("unchecked")
      public List<MappedLdapGroup> getMappedLdapGroups(final String dn) {
          final Query query = pm.newQuery(MappedLdapGroup.class, "dn == :dn");
          return (List<MappedLdapGroup>) query.execute(dn);
      }
docs: Retrieves a List of MappedLdapGroup objects for the specified DN.
  @param dn a String representation of Distinguished Name
  @return a List of MappedLdapGroup objects
  @since 1.4.0