Large pr

Summary by Bito

• Fixes a bug in OrderProcessingSystem.java by correcting the for loop condition to avoid processing an extra item.
• Enhances LibraryManagement.java to validate book availability before marking a book as returned.
• Introduces extensive new processing methods in LegacyApplication.java, ranging from process1 to process388, each implementing conditional arithmetic operations, updating a global counter, and caching results.
• Enhances order processing functionality through OrderProcessingSystem.java and test2.java, providing robust order management and notification mechanisms.
• Adds a new LibraryManagement system to facilitate book-related operations.
• Overall summary: Introduces new functionality and addresses critical bugs across LegacyApplication.java (extending legacy processing with arithmetic and caching logic), LibraryManagement (for book operations and availability validation), OrderProcessingSystem.java (order management with corrected loop condition), and test2.java (notifications), contributing to overall stability and correctness in the system's business logic.