[GSS] (6.4.z) Human task subject not returned in REST API response

In the response of the REST API(http://localhost:8080/kie-server/services/rest/server/queries/tasks/instances/pot-owners), task subject is not returned.
kie-server response:
~~~
<task-summary>
<task-id>1</task-id>
<task-name>HT</task-name>
<task-subject/>
<task-description>description</task-description>
~~~

If we use business-central REST API http://localhost:8080/business-central/rest/task/query , we can see task subject is populated in response.
business-central response:
~~~
<task-summary>
<id>1</id>
<name>HT</name>
<subject>subject</subject>
<description>description</description>
<status>Reserved</status>
~~~