According to https://docs.microsoft.com/en-us/graph/api/onlinemeeting-get?view=graph-rest-1.0&tabs=http you can get the information associated with an existing OnlineMeeting using the request
GET /users/{userId}/onlineMeetings/{meetingId}Unfortunately the response does not include the information whether users have really joined the OnlineMeeting (using its joinWebUrl).
With /attendeeReport something seems to exist for OnlineMeetings which have ended, but this is not possible for OnlineMeetings which have not ended, yet.
We need the joined user(s) information (the name would be enough) while the meeting has not ended.
Let me explain, why we need this:
One of our customers provides a link to start an OnlineMeeting on his webpage. The employees of our customer now receive a notification as soon as a web site visitor clicks this link (and so implicitly creates an OnlineMeeting). As many visitors now jump off (for example they don't want to install Teams or refuse to use the Chrome/Edge browser), unfortunately our customer's employees still receive the notification that an OnlineMeeting has been created, though the vistor never joined. In order to filter out these OnlineMeeting where a vistor has never joined, we need the information for a OnlineMeeting how many user(s) are joined currently.