question: @ RequestMapping ( value = "/{bookmarkId}" , method = RequestMethod . PUT ) public ResponseEntity < Bookmark > editBookmark ( @ PathVariable ( value = "username" ) String username , @ PathVariable ( value = "bookmarkId" ) int bookmarkId , @ RequestBody String json ) throws IOException , BookmarkNotFoundException , IllegalAccessException , InvocationTargetException { Optional < Bookmark > optional = bookmarksRepository . findByIdAndUserUsername ( bookmarkId , username ) ; if ( optional . isPresent ( ) ) { ObjectMapper mapper = new ObjectMapper ( ) ; Map < String , String > changeMap = mapper . readValue ( json , HashMap . class ) ; Bookmark bookmark = optional . get ( ) ; BeanUtils . populate ( bookmark , changeMap ) ; bookmark = bookmarksRepository . save ( bookmark ) ; return new ResponseEntity < > ( bookmark , HttpStatus . OK ) ; } else { throw new BookmarkNotFoundException ( "Bookmark not found id = " + bookmarkId ) ; } }
target:  A method to edit a bookmark.