Update migration-api-whats-new.md

Added as a new requirement, the mandatory use of SourceType when calling the Migration API.

Author: JoanneHendrickson

docs/apis/migration-api-whats-new.md

@@ -1,7 +1,7 @@
 ---
 title: "Migration API What's new"
 description: "Learn about the new features and updates to the Migration API."
-ms.date: 06/28/2022
+ms.date: 09/23/2022
 ms.reviewer: jhendr
 author: JoanneHendrickson
 ms.author: jhendr
@@ -16,6 +16,26 @@ ms.custom: admindeeplinkSPO
 
 Check here to see what features or updates have been added to the Migration API. Here's a summary of what's included.
 
-##  Fixes
+## New requirement
 
-- **Changes to how Import API handles users**. As a response to issues arising from broken OneDrive scenarios when importing duplicate users, the API now blocks and detect duplicate user entries in UserGroup.xml. For details see: [Entering user identifiers in UserGroup.xml](/sharepoint/dev/apis/migration-api-overview#entering-user-identifiers-in-usergroup.xml).
+Beginning January 1, 2023, the SourceType field will be mandatory when calling the Migration API. Starting October 1st, 2022, a warning message will be sent if the field is missing.
+
+**Accepted SourceType values:**
+
+- AmazonS3   
+- AzureStorage   
+- Box 
+- Dropbox   
+- Egnyte   
+- FileShare   
+- GoogleCloudStorage   
+- GoogleDrive   
+- MicrosoftStream   
+- OneDrive  
+- SharePointOnline   
+- SharePointOnPremServer    
+- Other
+
+## Fixes
+
+- **Changes to how Import API handles users**. As a response to issues arising from broken OneDrive scenarios when importing duplicate users, the API now blocks and detect duplicate user entries in UserGroup.xml. For details see: [Entering user identifiers in UserGroup.xml](/sharepoint/dev/apis/migration-api-overview#entering-user-identifiers-in-usergroup.xml).