He plugin: Null Pointer exception while running link scale tests

1) Start karaf
2) Do feature install odl-openflowplugin-flow-services-ui-li
3) Run mininet with 10 switches in fully mesh topology.
4) Check if controller goes out of memory.
5) Check if controller has null pointer exceptions in karaf.log
6) Check if controller has learned all the expected links (10*10-1)=90
7) If 4,5,6 works repeat step 3-6 with switch count 10 + step(5)
8) If any of the steps from 4 to 6 fail stop the test.
9) For Lithium Redesign I see Null Pointer exceptions @ switch count = 10
10) For Master branch I see Null Pointer exceptions @ switch count = 25
11) There robot results link for each branch is as below.

Lithium Redesign
https://jenkins.opendaylight.org/releng/job/openflowplugin-csit-periodic-1node-cds-link-scalability-daily-lithium-redesign-only-master/3/robot/report/log.html

Master Branch
https://jenkins.opendaylight.org/releng/job/openflowplugin-csit-periodic-1node-cds-link-scalability-daily-only-master/3/robot/report/log.html