Fix high severity issues reported by SonarCloud

[iluwatar]

SonarCloud is used for static code analysis. It currently reports 48 high severity issues.

See https://sonarcloud.io/project/issues?impactSeverities=HIGH&resolved=false&id=iluwatar_java-design-patterns

It is possible to run the same analysis on local machine using SonarLint plugin. See instructions at https://github.com/iluwatar/java-design-patterns/wiki/12.-IDE-instructions

Acceptance criteria

• High severity issues reported by SonarCloud have been fixed

[iluwatar]

Most of the high severity issues fixed by @k1w1dev, but still 18 remain. See https://sonarcloud.io/project/issues?impactSeverities=HIGH&resolved=false&id=iluwatar_java-design-patterns

[krishnagjsForGit]

I can start on these remaining issues.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. The issue will be unassigned if no further activity occurs. Thank you for your contributions.

[PALASH2201]

I'm new here, are all the issues fixed?

[PALASH2201]

I went to through this analysis https://sonarcloud.io/project/issues?impactSeverities=HIGH&resolved=false&id=iluwatar_java-design-patterns , mongoDB credentials were hardcoded, so I have added .env file and tested the changes, I have also added and updated dependencies in pom.xml. I have tested and it has passed. How to proceed now?

[PALASH2201]

Should I issue a PR for your review?

[PALASH2201]

@iluwatar I apologize for pinging you, but is this issue solved already, I have made some changes, just need your approval