Request header:
If-Modified-Since:Mon, 03 Nov 2014 12:51:29 GMT
This format is RFC1123_PATTERN_FORMAT and does not contain milliseconds.
For file serving, the file modified date contains milliseconds (resource.getLastModified()).
So DateUtils.handleIfUnmodifiedSince() and DateUtils.handleIfModifiedSince()
don't work as expected and even if the headers will match in request and response the file will be sent.
Maybe the file date should be rounded.
Thank you.