Spring Boot 3.x to 4.0 Migration

Step-by-step migration workflow. Topic details live in references/; load only the files relevant to the current step.

Rules

• Never read or print secrets (.env, credentials, tokens in properties files).
• Change one thing per step and run the test suite after each step; commit nothing you cannot build.
• Pin versions explicitly; never use latest or open-ended ranges.
• Check the official sources when unsure: the Spring Boot 4.0 Migration Guide on the Spring Boot GitHub wiki and the release notes on spring.io.

Workflow