fix: remove file from fileMap in online generator

[daniel-kmiecik]

PR checklist

• Read the contribution guidelines.
• Ran the shell script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh and ./bin/security/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates). Windows batch files can be found in .\bin\windows\.
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Description of the PR

• System.out.println statements were replaced with a logger
• logic for reading file bytes and deleting the file was extracted into separate methods
• a null check for g and its filename was added to return a 404 response instead of throwing an exception when the file does not exist in the map
• remove downloaded file from fileMap after download

[Copilot]

Pull Request Overview

This PR enhances error handling and code quality in the Swagger code generator's file download functionality. The changes replace System.out.println statements with proper logging, add null safety checks, ensure proper file cleanup after downloads, and extract file operations into dedicated methods for better maintainability.

• Replaced console output with SLF4J logger for better production logging
• Added null checks to prevent NullPointerExceptions when files don't exist in the map
• Implemented proper file cleanup by removing entries from fileMap after download

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
SwaggerResource.java	Refactored downloadFile method with logging, null checks, extracted helper methods, and file cleanup logic
SwaggerResourceTest.java	Added comprehensive test coverage for download scenarios including happy path, file removal, missing files, and path validation
pom.xml	Added Mockito dependencies to support the new test mocking requirements

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[ewaostrowska]

Please consider updating the documentation with a sentence about

• possible 404 when no file
• no authentication needed