update/insert Select field value
update or insert a new Select List (cascading) field option value via Plugin and Curl
install CustomFieldEditorPlugin "jiracustomfieldeditorplugin"
go to Add-Ons > Customfield Editor > Permission Editor
Add a user account to the field permission, this si the user that will be inserting new values via Curl request
Get the Field ID of the select field, both the parent and child option (in this case its 12600 for parent, 14042 child)
curl -u user:pw -X GET https://jiraserver/rest/jiracustomfieldeditorplugin/1.1/user/customfieldoptions/12600
[{"optionvalue":"Child1","id":14042,"sequence":0,"disabled":false},{"optionvalue":"Child2","id":14043,"sequence":1,"disabled":false},{"optionvalue":"Child3","id":14044,"sequence":2,"disabled":false},{"optionvalue":"Child4","id":14045,"sequence":3,"disabled":false},{"optionvalue":"Child5","id":14046,"sequence":4,"disabled":false},{"optionvalue":"Child6","id":14047,"sequence":5,"disabled":false},{"optionvalue":"Child7","id":14048,"sequence":6,"disabled":false}]
do a Curl request to insert a new value
# Update JIRA select field
curl -u user:pw -X POST "https://jiraserver/rest/jiracustomfieldeditorplugin/1.1/user/customfieldchildoption/12600/14042" -H "Content-Type: application/json" -d "{\"optionvalue\": myNewValue,\"disabled\": false}"