Response of GET /rest/api/2/user/properties always empty

Summary

As described here, a new REST API call was introduced in JIRA 7.0 that returns properties for a given user. However, it's always returning an empty array, no matter how many properties there are.

Expected behaviour

Return a set of properties for the given user.

Actual behaviour

An empty array is returned, which means no properties have been found for the given user.

Example

Call

localhost:8080/rest/api/2/user/properties?username=admin

Response

{"keys":[]}

Steps to Reproduce

1. Add a key-value pair under properties on a user profile in JIRA;
2. Try to list the property keys for this user with the below REST API call;

   http://<jira-url>/rest/api/2/user/properties?username=myuser
   

3. Observe the response returned is empty;

Workaround

At this point, there's no workaround for obtaining users' properties using a REST API call.