fix: GWT servlet review

[nicolatimeus]

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Brief description of the PR. [e.g. Added null check on object to avoid NullPointerException]

Reviewed and improved legacy GWT servlet code

[MMaiero]

Forcing merge.
The build succeeds locally but we are facing an issue in the CI connection to Sonar. An issue has been raised few weeks ago to the Eclipse Team: https://gitlab.eclipse.org/eclipsefdn/helpdesk/-/issues/4422