Camunda external class with protected engine-rest url

Hi ,
Currently working on camunda 7.21 engine where the engine rest is protected with access token.
Now i am trying to implement external class which has some action to be done outside the workflow.
so i have configuration as
Since the rest is protected…not able to access the external topic and getting below error

org.camunda.bpm.client.impl.EngineClientException: TASK/CLIENT-02001 Request ‘POST http://localhost:8080/engine-rest/external-task/fetchAndLock’ returned error: status code ‘500’ - message: null

Please advise on it.

@Camunda7Team can you please advise on above issue.