Appointment getEndTimeZone and getStartTimeZone empty

[reimac05]

There is only one exchange installation which manages several sites (on-premise Exchange 2010) . This exchange instance manages room resources for different countries. Therefore we provide the timezone when we book a meeting. But if I want to read the timezone of the appointment, it will always be empty?? I also tried to set the timezone for the mailbox, but without success.

See the following:

Mailbox mailbox = Mailbox.getMailboxFromString(roomMail.getRoomMailSmtp());
FolderId folderId = new FolderId(WellKnownFolderName.Calendar, mailbox);
CalendarFolder calendar = CalendarFolder.bind(exchangeService, folderId);
FindItemsResults<Appointment> appointments = calendar.findAppointments(
				new CalendarView(startForAppointmentSearch.toDate(), endForAppointmentSearch.toDate()));
		ArrayList<Appointment> appointmentList = appointments.getItems();
for (Appointment appointment1 : appointmentList) {

  appointment1.getStartTimeZone() -> IS NULL??
  appointment1.getTimeZone() -> IS always the same ((UTC+01:00) Amsterdam, Berlin, Bern, Rom, Stockholm, Wien)