Invalid mime type \"rss+xml\": does not contain '/'

Question

I am making a rest API call using rest template and where content type is application/json but the server return the response in rss+xml format

resTemplate.getMessageConverters().add(0,new StringHttpMessageConverter(StandardCharsets.UTF_8));       
ResponseEntity<String> response = resTemplate.exchange(requestEntity,String.class);

So I am getting Invalid mime type "rss+xmp": does not contain '/'

Header have only --> Content-Type="application/JSON"

I want the response in the same type which the server is sending and I should be able to handle the response return by the server without any error