have CoreLoader support XLSX

[TomTasche]

Closes #351

[claude]

Claude finished @TomTasche's task —— View job

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Claude Code has reviewed the pull request

Todo List:

• Read CoreLoader.java to understand the changes
• Analyze the diff for XLSX support implementation
• Review for code quality and best practices
• Check for potential bugs or issues
• Assess performance considerations
• Evaluate security concerns
• Consider test coverage needs
• Provide comprehensive review feedback

Code Review

Summary

This PR adds XLSX support to the CoreLoader class by updating the isSupported() method to recognize the MIME type for Excel files (application/vnd.openxmlformats-officedocument.spreadsheetml.sheet).

Changes Made

The key change is in the isSupported() method (lines 64-69):

• Added support for XLSX files when doOoxml flag is enabled
• The XLSX MIME type is now included alongside DOCX support
• PPTX support remains commented out with a TODO

Code Quality

✅ Good practices observed:

• The implementation follows the existing pattern for OOXML document support
• Proper use of the doOoxml flag to conditionally enable the feature
• Clean and minimal change that doesn't affect other functionality

Potential Issues

⚠️ Missing test coverage: No tests were added to verify XLSX file handling. Consider adding:

• Unit tests for isSupported() with XLSX MIME types
• Integration tests with sample XLSX files
• Edge case testing (corrupted files, large files, password-protected XLSX)

Performance Considerations

✅ The change has minimal performance impact as it only adds a string comparison to the existing condition check.

Security Concerns

⚠️ Input validation: While the MIME type check provides basic filtering, ensure the underlying CoreWrapper properly validates and sanitizes XLSX content to prevent:

• XML External Entity (XXE) attacks
• Zip bomb attacks (XLSX files are ZIP archives)
• Formula injection vulnerabilities

Suggestions for Improvement

1. Add comprehensive tests for XLSX support in CoreTest.java
2. Document the feature in the project README or API documentation
3. Consider enabling PPTX support as mentioned in the TODO comment (line 67)
4. Error handling: Ensure proper error messages for unsupported XLSX features or corrupted files

Overall Assessment

The implementation is straightforward and follows existing patterns. However, the lack of test coverage is concerning for a file format addition. I recommend adding tests before considering this feature complete.