code: public long getInstanceLength() {
          // See Content-Range in
          // http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
          String contentRange = (String)metadata.get(Headers.CONTENT_RANGE);
          if (contentRange != null) {
              int pos = contentRange.lastIndexOf("/");
              if (pos >= 0)
                  return Long.parseLong(contentRange.substring(pos+1));
          }
          return getContentLength();
      }
docs: Returns the physical length of the entire object stored in S3.
  This is useful during, for example, a range get operation.