Office 365 Integration Issue with ORC (with on-premise exchange service)

Summary:

At our organization, the Microsoft Exchange server(email, calendars) is on-prem. The Office 365 ORC integration with Oracle relies on Microsoft Graph API's and the on-prem version doesn't support it.As an alternate approach, we plan to house all the recruiters/Hiring Manager accounts on a sub domain on Azure AD and  they will still continue to have an email account on-prem as well. This setup will enable them to set up interview with the candidates and inturn the candidates will also have visibility to the Recruiters and hiring Managers calendar as the Azure Calendar will be exposed on the Oracle recruting side.The issue we see