Event Hubs bindings does not honor http status code

@FunctionName("HttpTrigger-EmailOutBound")
@EventHubOutput(name = "message", eventHubName = "eventHubTest", connection = "AzureEventHubConnection")
public HttpResponseMessage run(
@HttpTrigger(name = "httpRequestMessage", methods = {HttpMethod.POST}, authLevel = AuthorizationLevel.ANONYMOUS)
HttpRequestMessage> httpRequestMessage,
final ExecutionContext context) {
return httpRequestMessage
.createResponseBuilder(HttpStatus.UNAUTHORIZED)
.body("unauthorized")
.build();
}

Expected OutPut : HttpStatus Code : 401
Actual : HttpStatusCode: 200

Output:

{
"method": "",
"query": {},
"statusCode": "401",
"headers": {},
"enableContentNegotiation": false,
"body": "unauthorized"
}

Even the response body has the statusCode 401 , the actual response has 200.