Test branch1

Summary by Bito

• Fixes potential bugs in user data processing and concurrent operations, improving reliability in the user_manager class functionality.
• Improves security by laying groundwork for more secure and reliable user data processing through better encapsulation in the user_manager class.
• Fixes potential bugs related to data handling by updating public variables to private with renaming in the user_manager class.
• Adjusts the thread's maxSize assignment in test.java to correct potential bugs in concurrent operations.
• Updates the conditional check in Process_User_Data within test.java to address critical issues.
• Overall summary: Enhances the user_manager class in test.java by modifying field access levels to private, improving security and reliability through better encapsulation and bug fixes in user data processing and concurrent operations.