What is definition of issue and next of kin in california probate

No - "issue" are the children of the deceased; however, one still needs to list the names and addresses of the "issue" (children) of the deceased's siblings in case the will is not admitted into probate, or some other problem arises, or there is some dispute as to the validity of the will, or if the siblings are among the beneficiaries of the will, one of them may chose to not accept the devise, and their children might be potential heirs depending on the terms of the will. There are lots of possibilities....