Q:

Jackson adds wrapper for List

I have controller which returns an ArrayList of objects:
@GetMapping("/{access_token}/connected_instagram_accounts")
public ResponseEntity<List<InstagramAccountDTO>> getConnectedInstagramAccounts(@PathVariable("access_token") String accessToken) {
    log.debug("InstaramController.getConnectedInstagramAccounts() was called.  access_token = {}", accessToken);

    List<InstagramAccountDTO> result = instagramService.getAllConnectedInstagramAccounts(accessToken);

    return new ResponseEntity<>(result, HttpStatus. OK);
}

In Postman i see that this endpoints returns following result:
{
    "ArrayList": []
}

But i expect that the ArrayList shouldn't have any wrapper object, and i'm expecting following result:
[]

I tried to check serialization in debugger and see that jackson serializes it in correct way. 

Where do i need to look for the problem?  What class is responsible for serializing ResponseEntity? 

A:

As usually, it was my silly mistake.  I have previously added following settings for jackson and forgot about it:
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.configure(SerializationFeature. WRAP_ROOT_VALUE, true);

So, it was the reason why jackson added wrapper object for my list.