Issue Summary

Certain JQLs which accept a list of terms, return all issues the current user has permission to see when the list of terms is empty.

e.g. fooUserField in membersOf(barGroup) where fooUserField is a custom field of type "User Picker & Group Searcher", will return all issues when barGroup is empty.

Steps to Reproduce

1. Create a custom field of type "User Picker & Group Searcher" e.g. fooUser
2. Create an empty group e.g. barGroup
3. Search using the following JQL

fooUser in membersOf(barGroup)

Expected Results

No issues are returned

Actual Results

All issues which the user has permission to see.

Workaround

Disable the com.atlassian.jira.search.api feature flag.