Nullable variable and try-with-resource handling.
https://sonar.onap.org/project/issues?id=org.onap.vfc.nfvo.wfengine%3Aworkflow-engine-mgr-service&open=AWH4XKnARGy6eclHCx_W&resolved=false&types=BUG%2CVULNERABILITY
https://sonar.onap.org/project/issues?id=org.onap.vfc.nfvo.wfengine%3Aworkflow-engine-mgr-service&open=AWH4XKnARGy6eclHCx_P&resolved=false&types=BUG%2CVULNERABILITY