@GetMapping("/stream")
public ResponseEntity<InputStreamResource> stream(HttpServletRequest request) {
    // Let's say I have a big input stream for which I want to:
    // - provide the Content-Length and ETag (to avoid a heavy calculation by ShallowEtagHeaderFilter)
    // - allow caching through If-None-Match
    return ResponseEntity.ok()
            .contentType(MediaType.TEXT_PLAIN)
            .eTag("demo") // -> overriden by ShallowETagHeaderFilter
            .contentLength(123) // -> overriden by ShallowETagHeaderFilter
            .cacheControl(CacheControl.maxAge(1, TimeUnit.HOURS))
            .body(new InputStreamResource(new ByteArrayInputStream("demo".getBytes())));
}