I am attempting to use the NiFi StandardOauth2AccessTokenProvider 1.23.2 with the ConsumeIMAP processor in order to retrieve emails from Microsoft Outlook.

When I configure using a grant type of either Client Credentials or Refresh Token, the "Can acquire token" validation always fails with a 400 response code.

Upon examining the logs, the error reads:

ERROR [Verify Controller Service Config Thread-1] o.a.n.o.StandardOauth2AccessTokenProvider StandardOauth2AccessTokenProvider[id=ba2358f5-018b-1000-e706-d1406dd00474] OAuth2 access token request failed [HTTP 400], response:
{"error":"invalid_request","error_description":"AADSTS900144: The request body must contain the following parameter: 'grant_type'. Trace ID: 42b51bc0-3865-441e-abb2-200be69b6a00 Correlation ID: 1d0d67de-c1c3-4f0c-9f82-528b027ba18b Timestamp: 2023-11-13 14:41:12Z","error_codes":[900144],"timestamp":"2023-11-13 14:41:12Z","trace_id":"42b51bc0-3865-441e-abb2-200be69b6a00","correlation_id":"1d0d67de-c1c3-4f0c-9f82-528b027ba18b","error_uri":"https://login.microsoftonline.com/error?code=900144"}

 It would seem that the request is not setting the Grant Type correctly. I am able to create the request for a token outside of NiFi just fine when setting grant_type to client_credentials or refresh_token.

Is it possible to get this working or is this just a bug with this particular controller service?