Receiving null in autocomplete URL in createmeta

Sumit Sinha

Jira version : 7.2

When I request createmeta in the autocomplete URLs for things like `Assignable users` i get null in the IssueKey query parameter. While on cloud version it works perfectly.

Like : 

"assignee": {
 "required": false,
 "schema": {
 "type": "user",
 "system": "assignee"
 },
 "name": "Assignee",
 "autoCompleteUrl": "http://2342.ngrok.io/rest/api/latest/user/assignable/search?issueKey=null&username=", "hasDefaultValue": false,
 "operations": [
 "set"
 ]
 }

Why is it so?