Timesheet Grouped by Jira Service Desk Customers

JIRA Service Desk Customers are actually the reporter of the issues they have raised on the portal, so if you create a timesheet report that groups on 'reporter' you are affectively grouping on 'customers'. If you need the issues reported by non-customers to be excluded you can select your timesheet accordingly. For example you can create a timesheet report for JIRA Service Desk Organization or create a special filter that contains only the customers you want and than create a timesheet for that filter.