@Override
  public void deleteGroups(Set<GroupRequest> requests) throws AmbariException {
    for (GroupRequest request: requests) {
      LOG.debug("Received a delete group request, groupname={}", request.getGroupName());
      final Group group = users.getGroup(request.getGroupName());
      if (group != null) {
        users.removeGroup(group);
      }
    }
  }
Computes os-dependent packages for service/host. Does not take into
account package dependencies for ANY_OS. Instead of this method
you should use getPackagesForServiceHost()
because it takes into account both os-dependent and os-independent lists
of packages for service.
@param hostParams may be modified (appended SERVICE_REPO_INFO)
@return a list of os-dependent packages for host
ambari-server/src/main/java/org/apache/ambari/server/controller/AmbariManagementControllerImpl.java