Fixing sonar issues in whole file
https://sonar.onap.org/dashboard?id=org.onap.appc%3Aappc-config-flow-controller-provider%3Asrc%2Fmain%2Fjava%2Forg%2Fonap%2Fappc%2Fflow%2Fcontroller%2FexecutorImpl%2FGraphExecutor.java