Exceptions seen when controller connected to Mininet

I see these exceptions constantly rolling when the controller is connected to mininet:
java.lang.NullPointerException: null
at org.opendaylight.yang.gen.v1.urn.opendaylight.group.statistics.rev131111.OpendaylightGroupStatisticsService$$Broker$DirectProxy.getAllGroupStatistics(OpendaylightGroupStatisticsService$$Broker$DirectProxy.java) ~[na:na]
at org.opendaylight.controller.md.statistics.manager.StatisticsProvider.sendAllGroupStatisticsRequest(StatisticsProvider.java:161) ~[na:na]
at org.opendaylight.controller.md.statistics.manager.StatisticsProvider.statsRequestSender(StatisticsProvider.java:140) ~[na:na]
at org.opendaylight.controller.md.statistics.manager.StatisticsProvider.access$000(StatisticsProvider.java:43) ~[na:na]
at org.opendaylight.controller.md.statistics.manager.StatisticsProvider$1.run(StatisticsProvider.java:103) ~[na:na]
at java.lang.Thread.run(Thread.java:724) ~[na:1.7.0_25]
2013-11-27 19:58:31.266 PST [Thread-26] INFO o.o.c.m.s.manager.StatisticsProvider - Number of connected nodes : 7
2013-11-27 19:58:31.266 PST [Thread-26] INFO o.o.c.m.s.manager.StatisticsProvider - Send request for stats collection to node : Uri [_value=openflow:1])
2013-11-27 19:58:31.267 PST [Thread-26] ERROR o.o.c.m.s.manager.StatisticsProvider - Exception occurred while sending stats request : {}
java.lang.NullPointerException: null
at org.opendaylight.yang.gen.v1.urn.opendaylight.group.statistics.rev131111.OpendaylightGroupStatisticsService$$Broker$DirectProxy.getAllGroupStatistics(OpendaylightGroupStatisticsService$$Broker$DirectProxy.java) ~[na:na]
at org.opendaylight.controller.md.statistics.manager.StatisticsProvider.sendAllGroupStatisticsRequest(StatisticsProvider.java:161) ~[na:na]
at org.opendaylight.controller.md.statistics.manager.StatisticsProvider.statsRequestSender(StatisticsProvider.java:140) ~[na:na]
at org.opendaylight.controller.md.statistics.manager.StatisticsProvider.access$000(StatisticsProvider.java:43) ~[na:na]
at org.opendaylight.controller.md.statistics.manager.StatisticsProvider$1.run(StatisticsProvider.java:103) ~[na:na]
at java.lang.Thread.run(Thread.java:724) ~[na:1.7.0_25]
2013-11-27 19:58:31.267 PST [Thread-26] INFO o.o.c.m.s.manager.StatisticsProvider - Number of connected nodes : 7
2013-11-27 19:58:31.267 PST [Thread-26] INFO o.o.c.m.s.manager.StatisticsProvider - Send request for stats collection to node : Uri [_value=openflow:1])
2013-11-27 19:58:31.269 PST [Thread-26] ERROR o.o.c.m.s.manager.StatisticsProvider - Exception occurred while sending stats request : {}

The exceptions need to be cleaned up. The probably impact statistics collection from switches, but I did not have a chance to test stats collection