Environment:
Build#1688 (05/20)
Switch Type: CPqD

Problem:
FlowMeterStats & FlowGroupStats => MetricDetails field populated with Null.

Karaf output:
===========
opendaylight-user@root>tsdr:list FlowMeterStats
TimeStamp = 05/22/2015 11:37:23|MetricName = ByteInCount|MetricValue = 0|MetricCategory = FlowMeterStats|MetricDetails = null

opendaylight-user@root>tsdr:list FlowGroupStats
TimeStamp = 05/22/2015 11:36:23|MetricName =ByteCount|MetricValue = 0|MetricCategory = FlowGroupStats|MetricDetails = null

Note:
1.This issue appliable for both Hbase & H2 DataStore.