code: public List<CmsOrganizationalUnit> getOrganizationalUnits(
          CmsDbContext dbc,
          CmsOrganizationalUnit parent,
          boolean includeChildren)
      throws CmsException {
  
          if (parent == null) {
              throw new CmsIllegalArgumentException(Messages.get().container(Messages.ERR_PARENT_ORGUNIT_NULL_0));
          }
          return getUserDriver(dbc).getOrganizationalUnits(dbc, parent, includeChildren);
      }
docs: Returns all child organizational units of the given parent organizational unit including
  hierarchical deeper organization units if needed.<p>
  
  @param dbc the current db context
  @param parent the parent organizational unit, or <code>null</code> for the root
  @param includeChildren if hierarchical deeper organization units should also be returned
  
  @return a list of <code>{@link CmsOrganizationalUnit}</code> objects
  
  @throws CmsException if operation was not successful
  
  @see org.opencms.security.CmsOrgUnitManager#getOrganizationalUnits(CmsObject, String, boolean)