How do I return Http Response Content Length for ResponseEntity<List<Object>> without formatting issues or losing data from my response body?

Question

I'm trying to set the content length of my ResponseEntity<List> but the full list isn't returned in the response. I tried something like

    long contentLength = staticMethodGetsContentLength(List<Object> objectList);
    HttpHeaders headers = new HttpHeaders();
    headers.add("Content-Length", String.valueOf(contentLength));
    return Response.ok().headers(headers).body(objectList);

and then what is returned is a JSON list like

[ { "data": "data"

without closing brackets or the full list of objects. Is there an easy fix for this or an alternative to what I'm doing?