The current behavior of the bundle when the client provides both If-None-Match and If-Modified-Since headers does not match the HTTP/1.1 spec. According to the spec, A recipient MUST ignore If-Modified-Since if the request contains an If-None-Match header field (https://tools.ietf.org/html/rfc7232#section-3.3). The current behavior of the bundle is to return a 304 if the check on either condition would on its own result in a 304.

For example, if the client specifies an eTag in the If-None-Match header that does not match the server's eTag for the entity, and the client specifies a time in the If-Modified-Since header that is later than the server's last modified time for the entity, the server will respond with a 304. It should instead respond with a 200 and the entity.