Merge branch 'open-issues' into 'master'

            for fqdn in subelement_thr.keys():

                subelement_thr[fqdn].join()

            if all(self.empty_succeeded[fqdn] for fqdn in device_to_turn_off):

            if all(self.empty_succeeded[fqdn] for fqdn in device_to_turn_off) and device_to_turn_off:

                result_code = ResultCode.FAILED

                for fqdn in device_to_turn_off:

                    try:

                        self.logger.info('Sending Off Command...')

                        (result_code, message) = device._sc_subarray_proxies[fqdn].Off()

                    except tango.DevFailed as tango_err:

                        message = str(tango_err.args[0].desc)

                        result_code = ResultCode.FAILED

                if result_code == ResultCode.FAILED:

                    self.logger.error("Off command failed on device {}".format(fqdn))