Fix 2 potential NPE in ArtifactsBusinessLogic introduced by SDC-2754.
https://sonarcloud.io/project/issues?id=onap_sdc&issues=AXGUikEybfDtRnIiyw7U&open=AXGUikEybfDtRnIiyw7U
https://sonarcloud.io/project/issues?id=onap_sdc&issues=AXGUikEybfDtRnIiyw7V&open=AXGUikEybfDtRnIiyw7V