Place and later release a legal hold on custodian mailboxes and sites via the Microsoft Purview eDiscovery API in Microsoft Graph.

Verified steps

1. Assign the calling app/user the eDiscovery Manager or eDiscovery Administrator Purview role and grant the corresponding Microsoft Graph eDiscovery permissions.
2. Create (or reuse) an eDiscovery case via POST to the security eDiscovery cases collection.
3. Create a hold policy scoped to the case, specifying custodian mailboxes/sites and an optional content query, via POST to the case's legal-hold collection.
4. Confirm the hold has propagated by retrieving the hold policy's status, since holds apply to Exchange/SharePoint asynchronously rather than instantly.
5. Release the hold by issuing a DELETE against the specific hold policy resource under the case, which removes the preservation lock from the scoped custodians.
6. Build against the current microsoft.graph.security eDiscovery resources rather than the deprecated microsoft.graph.eDiscovery namespace for new integrations.