Spring Boot Password Change Feature

I need a Spring Boot expert to finalize an almost complete password change feature. The system should allow users to change their passwords in the Settings module, with the following functionalities:
- Pre-filling user information from the User table.
- New password input.
- Verification of password against security requirements using the Passay library.
- Encryption of the new password and updating it in the User table.
- Displaying a confirmation of the password change.

You will also need to handle an alternative flow for invalid passwords, where the system displays an error and the user can try inputting a new password.

You don't need to worry about the integration with Docker, PostgreSQL, or Thymeleaf, all of that is already set up. Your main focus is on the completion of this password change feature.

Skills and experience ideal for this job:
- Proficient in Spring Boot
- Familiar with Docker and PostgreSQL
- Experience with user authentication and password encryption
- Knowledge of the Passay library
- Good understanding of MVC architecture