call api 'hostgroup.get' with 'maintenanceids' parameter.

hostgroup AA has multiple maintenances XX and YY,
but return hostgroup object has only one maintenanceid XX's ID or YY's ID

source code of CHostGroup.php
function get()
section of building results of maintenanceids

2.0.13 : line 447-448
2.2.6 : line 386-387

checking result array of 'maintenanceid' entity then
initialized 'maintenances' entity

it causes hostgroup has multiple maintenance objects, but
result contains only last maintenance instance's id.

to fix this issue:
checking process of 'isset' method's parameter,
'maintenanceid' to 'maintenances'

–
sorry my poor english...

see also:
this issue related contents in Japanese Language;
Zabbix-JP user forum at
http://www.zabbix.jp/node/2935