NettyUtils: added safe check for null pointers. Added regression tests.

[martinKindall]

Motivation and Context

#3935

Modifications

Added null-pointer check and regression tests to increase coverage.

Testing

The included tests were tested running the unit tests of that module with ./mvnw package
Testing environment

JDK: java-1.8.0-amazon-corretto-devel
OS: Amazon Linux 2 Kernel 5.10, 64 bits.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• I have read the CONTRIBUTING document
• Local run of mvn install succeeds
• My code follows the code style of this project
• My change requires a change to the Javadoc documentation
• I have updated the Javadoc documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed
• I have added a changelog entry. Adding a new entry must be accomplished by running the scripts/new-change script and following the instructions. Commit the new file created by the script in .changes/next-release with your changes.
• My change is to implement 1.11 parity feature and I have updated LaunchChangelog

License

• I confirm that this pull request can be released under the Apache 2 license

[zoewangg]

@martinKindall thank you for submitting the PR! Running tests now

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
9 Code Smells

93.8% Coverage
0.0% Duplication

[debora-ito]

@all-contributors please add @martinKindall for code.

[allcontributors]

@debora-ito

I've put up a pull request to add @martinKindall! 🎉