Solution
First we need to run the following lines of code to connect to Exchange Online.
$UserCredential = Get-Credential $ExchangeSession = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential $UserCredential -Authentication Basic -AllowRedirection Import-PSSession $ExchangeSession
Once we are connected we can run these PowerShell command towards the mailbox in question, [email protected]. The first line will set the permissions for the default user to Reviewer, giving all users permission to read all items in the meeting room calendar. The second line will set the calendar processing rules in order to not delete the subject upon accepting the meeting.
Set-MailboxFolderPermission -Identity [email protected]:\Calendar -User default -AccessRights Reviewer Set-CalendarProcessing -Identity [email protected] -DeleteSubject $False -AddOrganizerToSubject $True
That’s all! Now the meeting room calendar will show the meeting subject instead of busy. If you don’t want to add the meeting organizer to the subject you can of course set this to $False instead. Johnny User rescheduled the meeting after the processing rules were altered, causing the calendar to now show the subject for his meeting.
"{\"@odata.context\":\"https://graph.microsoft.com/v1.0/$metadata#users('bjroom1%40cndotnetcms.onmicrosoft.com')/calendar/calendarView(start,subject,end)\",\"value\":[{\"@odata.etag\":\"W/\\\"BL4Bu4durEO1ANIoXDCtRQAAIWFULA==\\\"\",\"id\":\"AAMkAGEwZTJiMzZlLTE1NDItNDA0ZS1iNGU2LWRkYjI0ZDE1YjJjZQBGAAAAAACK5GxVHnjfSKLrOTV9vGGMBwAEvgG7h26sQ7UA0ihcMK1FAAAAAAENAAAEvgG7h26sQ7UA0ihcMK1FAAAhYZZYAAA=\",\"subject\":\"\\u674e \\u4e07\\u5b9d \",\"start\":{\"dateTime\":\"2020-02-20T11:30:00.0000000\",\"timeZone\":\"UTC\"},\"end\":{\"dateTime\":\"2020-02-20T13:00:00.0000000\",\"timeZone\":\"UTC\"}}]}"