UWL User decision note mandatory

Hi Experts,

In my UWL config, i want approval and rejection comments mandatory....
Currently only Rejection is working a mandatory.

How to modify the below XML to make approval also mandatory ?
Can i change value="true" to value="mandatory" ?

<Actions>
<Action name="approve" groupAction="yes" handler="UserDecisionHandler" returnToDetailViewAllowed="yes" launchInNewWindow="no">
<Properties>
<Property name="decisionKey" value="1"/>
<Property name="UserDecisionTitle" value="Enter Approval or Rejection Comment please"/>
<Property name="UserDecisionNote" value="true"/>
</Properties>
<Descriptions default="Approve"/>
</Action>
<Action name="reject" groupAction="yes" handler="UserDecisionHandler" returnToDetailViewAllowed="yes" launchInNewWindow="no">
<Properties>
<Property name="decisionKey" value="2"/>
<Property name="UserDecisionTitle" value="Enter Approval or Rejection Comment please"/>
<Property name="UserDecisionNote" value="mandatory"/>
</Properties>
<Descriptions default="Reject"/>
</Action>
</Actions>

Please help...

Thanks & Regards,
Shiva