Java Function for Excel to PDF Conversion

I need a Java function that replicates the 'ExceltoPDF' functionality from the ILOvePDF portal. The function should handle XLS, XLSX, and CSV formats, preserving the formatting and layout from the original Excel file as closely as possible.

Key Requirements:
- Convert each sheet in a multi-sheet Excel file into a separate PDF
- Maintain the output format similar to the ILOvePDF portal
- Support for Excel file formats: XLS, XLSX, and CSV
- Create a CDK to include this package
- Create separate package for integration tests

Ideal Skills and Experience:
- Proficiency in Java
- Extensive experience with Excel file handling and PDF generation
- Familiarity with the ILOvePDF portal's conversion process
- Attention to detail for preserving formatting and layout.