JavaParser should favor public classes when naming source inputs

[ammachado]

What's changed?

This a follow-up on #4040, JavaParser should try to use public class names, when available.

What's your motivation?

Identified while testing #4030

Anything in particular you'd like reviewers to focus on?

No

Anyone you would like to review specifically?

No

Have you considered any alternatives or workarounds?

You can provide the correct source path when calling the Java Parser directly, but not when the parser is being called by a JavaTemplate.

Any additional context

No

Checklist

• I've added unit tests to cover both positive and negative cases
• I've read and applied the recipe conventions and best practices
• I've used the IntelliJ IDEA auto-formatter on affected files