Filter records that have exactly one value in Group Picker (multiple groups) custom field

Problem definition

Currently, Jira JQL cannot filter issues that have exactly single value in Group Picker (multiple groups) field.

Example:

• If we have a field called "Responsible Team" and if the custom field values are "Team A", "Team B" and many others, there is no way to filter issues that have only "Team A" value, but not any other value (for many custom field values, it does not make sense to use NOT IN operator.
• The following JQL cannot be used

  "Responsible Team" = "Team A"

  as it will return issues that have "Team A" but also any other values together with "Team A".

Suggested resolution

Implement JQL function that will return issues that have exactly one specified value in the Group Picker custom field.