public static ClassicHttpResponse make304Response() {
        return new BasicClassicHttpResponse(HttpStatus.SC_NOT_MODIFIED, "Not modified");
    }
Generates a response body with random content.
 @param nbytes length of the desired response body
 @return an {@link HttpEntity}
httpclient5-cache/src/test/java/org/apache/hc/client5/http/impl/cache/HttpTestUtils.java