Thanks @Vijayalakshmi_S , The datepicker is being shown now to the
assignee. However, can you please mention where the data for that
datepicker is saved. I tried following
https://helpx.adobe.com/ca/experience-manager/6-3/sites/developing/using/workflows-step-ref.html#ParticipantStepsandChoosers
and added name as './datetimepicker'. But I don't see any data
associated with the datepicker for the instance under
/var/workflow/instances. I do see other data for the instance like
assignee, model, co...