Prior to this change, trying to set an unquoted ETag with `ResponseEntity`'s API would throw an `IllegalArgumentException`. This commit automatically quotes ETag values set using ResponseEntity. Issue: SPR-13378
Prior to this change, trying to set an unquoted ETag with `ResponseEntity`'s API would throw an `IllegalArgumentException`. This commit automatically quotes ETag values set using ResponseEntity. Issue: SPR-13378