private static ResponseHeaders sanitizeHeaders(ResponseHeaders headers) {
        requireNonNull(headers, "headers");
        if (headers == defaultHttpHeaders) {
            return headers;
        }
        return ensureContentType(ensureHttpStatus(headers));
    }
Returns a newly created JSON Lines response from the specified {@code content}.

<p>Note that this method is intentionally hidden from the public API for use only with
{@code ScalaPbResponseConverterFunction} and {@code ProtobufResponseConverterFunction}.
Because the {@code contentConverter} can easily produce a malformed string which violates the
<a href="https://jsonlines.org/">JSON format</a>.

@param headers the HTTP headers supposed to send
@param content the object supposed to send as contents
@param trailers the HTTP trailers
@param contentConverter the function which converts the content object into a UTF-8 JSON string.
core/src/main/java/com/linecorp/armeria/server/streaming/JsonLines.java