3322328 - Generate Auth Token error: "The given value for token is null and will NOT be saved to the Database"

Trying to configure sender mail channel with OAuth 2.0

Getting the following error when trying to generate the refresh token:

• In the browser bellow exception can occur: 
  Auth Code is retrieved successfully. Attempting to retrieve the Auth Token.

Status information:

RuntimeException occurred while retrieving Access/Refresh Token. Please collect and check XPI Trace for further information.

Access/Refresh token can not be retrieved. Please collect and check XPI Trace for further information. 

• In XPI INSPECTOR TRACE example 100 bellow exception can be found:

RuntimeException occurred while retrieving Access/Refresh Token : java.lang.NullPointerException: The given value for token is null and will NOT be saved to the Database.
 at com.sap.aii.af.sdk.xi.oauth.cache.OAuth20TokenCache.checkForNullValue(OAuth20TokenCache.java:128)
 at com.sap.aii.af.sdk.xi.oauth.cache.OAuth20TokenCache.addToken(OAuth20TokenCache.java:52)[...]

• SAP NetWeaver Process Integration
• SAP NetWeaver Process Orchestration

client secret value, client secret ID, auth token, refresh Token, token is null, will NOT be saved to the Database, new client secret , KBA , BC-XI-CON-MAI , Mail Adapter , Problem