code: def explode_contact_groups_into_contacts(item, contactgroups):
          
          if not hasattr(item, 'contact_groups'):
              return
  
          # TODO : See if we can remove this if
          cgnames = ''
          if item.contact_groups:
              if isinstance(item.contact_groups, list):
                  cgnames = item.contact_groups
              else:
                  cgnames = item.contact_groups.split(',')
          cgnames = strip_and_uniq(cgnames)
          for cgname in cgnames:
              contactgroup = contactgroups.find_by_name(cgname)
              if not contactgroup:
                  item.add_error("The contact group '%s' defined on the %s '%s' do not exist"
                                 % (cgname, item.__class__.my_type, item.get_name()))
                  continue
              cnames = contactgroups.get_members_of_group(cgname)
              # We add contacts into our contacts
              if cnames:
                  if hasattr(item, 'contacts'):
                      # Fix #1054 - bad contact explosion
                      # item.contacts.extend(cnames)
                      item.contacts = item.contacts + cnames
                  else:
                      item.contacts = cnames
docs: Get all contacts of contact_groups and put them in contacts container
  
          :param item: item where have contact_groups property
          :type item: object
          :param contactgroups: all contactgroups object
          :type contactgroups: alignak.objects.contactgroup.Contactgroups
          :return: None