**GovCareers – Government Job Finder (Core Java)**

I need a Core Java-based web application, GovCareers, designed to find government job listings and provide detailed application instructions. The web app should also have a feature for building and downloading resumes in PDF format. I don't need a UI or deployment, just the core functionality.
(Please add comments in the code stating the function of the lines of code )

Key Features:
- User Interactions: The app should support searching and filtering job listings, viewing detailed job application instructions, and generating and downloading a resume in PDF format.
- Job Listings Sources: The job listings should be fetched from official government websites, job listing aggregators, and government job portals.
- Job Listings Format: The job listings should be displayed as text with basic formatting.

Ideal skills and experience for this job include:
- Strong proficiency in Core Java
- Experience with web scraping / data fetching from various sources
- Understanding of resume building and PDF generation
- Ability to structure information in a user-friendly way.