Column taskId is not returned in advanced query for Task table in JBoss BPM Suite 6

Issue

We are creating a new advanced query, we send the content below to the following URL: http://host:8080/kie-server/services/rest/server/queries/definitions/myQuery:

<query`definition>
    <query-name>myQuery</query-name>
    <query-source>java:/MyDS</query-source>
    <query-expression>select * from Task</query-expression>
    <query-target>TASK</query-target>
</query-definition>

The query has been created. When we hit the URL:

http://host:8080/kie-server/services/rest/server/queries/definitions/myQuery/data?mapper=UserTasks

The following XML content is returned:

<task-instance-list>
<task-instance>
<task-priority>0</task-priority>
<task-name>MyTask</task-name>
<task-status>Ready</task-status>
<task-created-on>2018-0307T01:49:23.236-04:00</task-created-on>
<task-activation-time>2018-04-07T12:49:05.236-04:00</task-activation-time>
<task-process-instance-id>16</task-process-instance-id>
<task-process-id>myorg.myprocess</task-process-id>
<task-container-id>someContainer</task-container-id>
</task-instance>

But if you look at above result , we don't find taskid as part of the response xml. I tried with other mappers but taskid is not part of the response. Please can you let us know if we are making any mistake here ?