add_hostgroup( params )
@icinga.add_hostgroup(host_group: 'foo', display_name: 'FOO')
delete_hostgroup( params )
@icinga.delete_hostgroup(host_group: 'foo')
hostgroups( params )
@icinga.hostgroups(host_group: 'linux-servers')
hostgroups
@icinga.hostgroups
exists_hostgroup?( hostgroup )
@icinga.exists_hostgroup?('linux-servers')