Automatically generated persistence id of the data object is present as a draggable component in the form created from the Data Object. Pere Fernandez Perez has confirmed, this should be filtered out from the editor.
One of the issues, it causes during runtime is when used as a column in Multiple Subform and several lines in the MS are generated, on submit of the form, you get error like this:
ERROR: Unexpected error occurred: org.kie.server.client.KieServicesHttpException:Unexpected HTTP response code when requesting URI 'http://localhost:8080/kie-server/services/rest/server/containers/attendance_1.0.0-SNAPSHOT/processes/attendance.track-worktime/instances'! Error code: 500, message: Unable to create response: [attendance.track-worktime:4 - add the data to Timesheet:5] -- org.hibernate.PersistentObjectException: detached entity passed to persist: orgunit.attendance.TimesheetLine