Modernization

Modernization guides help agents evolve existing Java applications toward current LTS Java versions, Jakarta namespaces, and maintainable structure—without rewriting for novelty.

Common modernization targets

Java 8/11 → Java 17/21
javax.* → jakarta.* where required by current frameworks
Legacy build layouts → clearer module/package structure
Missing tests → baseline HTTP and persistence tests
Ad-hoc configuration → type-safe configuration

Prompt patterns

Modernize this Spring Boot application to Java 21 and current Spring Boot 3.x.
Keep behavior stable, update Jakarta imports, and fix tests.

Identify dead code and unsafe defaults in this service.
Propose a minimal PR-sized modernization plan before editing.

Working agreements

Prefer incremental, reviewable changes.
Keep behavior stable unless the user asks for a redesign.
Update tests in the same change set when APIs move.
Record unsupported framework jumps as limitations.