Will CalendarItemId and Global Unique ID(GUID) change when moving mailboxes in a Hybrid Exchange environment (On-Boarding)

Hi

We have an application using ews-java-api to access the calendars of users and resources in Exchange Server.

When moving resource- and user mailboxes from On-Premise Exchange to Exchange Online (On-Boarding), will CalendarItems ItemId and Global Unique ID change after the move?

I mean Global Unique ID is the value, that can be accessed as an ExtendedProperty (MapiProperty) with value 3.

ExtendedPropertyDefinition GUID_DEFINITION = new ExtendedPropertyDefinition(DefaultExtendedPropertySet.Meeting, 3, MapiPropertyType.Binary);

Thanks in advance!

Br, Béla Borbély