Java Spring Boot Security & Code Quality

I need a comprehensive guide on best practices for Java Spring Boot development, focusing equally on security and code quality.

Key areas to cover include:

Security:
- Authentication and authorization
- Data encryption
- Vulnerability scanning and patching

Code Quality:
- Code readability and maintainability
- Unit testing and test coverage
- Code performance optimization

Ideal Skills and Experience:
- Expertise in Java Spring Boot
- Strong background in application security
- Experience with code quality metrics and improvement techniques
- Familiarity with unit testing frameworks

Deliverables should be practical and applicable.