SmartOrder — Part 5: The Commons Layer — Shared Infrastructure Done Right

The article explores SmartOrder's commons layer, a deliberately structured multi-module shared library that eliminates boilerplate across microservices by providing generic CRUD abstractions, AOP-based observability, custom Jackson modules, and test utilities. It is split into three sub-modules (commons-business, commons-service, service-test) with intentional dependency separation, and uses reflection-based field protection to automatically exclude audit fields from updates via a convention-over-configuration approach.