Umlaut characters not showing in Hipchat notification

Steps to reproduce

1. Create Bamboo plan name with umlaut characters. Example: teståäöÜmlaut
2. Add notification scheme to Hipchat
3. Run plan

Observed behavior

The umlaut characters disappears in the notifation: teståäöÜmlaut --> testmlaut

Notes

Issue only affects Hipchat notification. Notification to IM Address works fine.