Shred the rotisserie chicken. (See note below.) Add to a large mixing bowl along with remaining ingredients - onion, celery, grapes, and nuts. Stir to combine.
Add the mayonnaise and curry powder and mix well. Test for seasoning - if needed add salt and pepper. (When using a rotisserie chicken, I haven't found additional seasoning necessary.)
This makes an amazing wrap. Add spinach, tomatoes, onion, if desired. Fold over the ends and wrap burrito style, or enjoy as is. One of our favorite easy lunches!
Notes
I find shredded chicken holds the dressing better than chopped chicken. It's my personal preference.