org.eclipse.rap.rwt.client.service.ClientInfo.getClientTimezoneOffset() returns invalid value after a daylight saving change

[abzycdxw65]

The RAP framework's service method org.eclipse.rap.rwt.client.service.ClientInfo.getTimezoneOffset() from Bug 329007 and Bug 390435 returns a wrong value after there was a daylight saving transition with a change of the time zone offset.

The timezoneOffset field from org.eclipse.rap.rwt.internal.client.ClientInfoImpl is set only once in the very first RWT message request of a UI session. RWTMessageHandler.workAroundMissingReadData does a check, if it is the initial request with counter 0.

Example: In time zone Europe/Berlin there is a daylight saving change on October 29, 2023. After the switch from 02:59:59 to 02:00:00 the offset to UTC changes from 2 hours to 1 hour.

If a UI session was started before 02:59:59 in summer time (UTC+02:00), getClientTimezoneOffset() correctly returns -120 minutes. But after the switch to 02:00:00 (UTC+01:00), it still returns -120 minutes, whereas -60 minutes would be the correct value.