When a field or method is annotated with JPA schema annotations, check if a corresponding nullability annotation is present that aligns with the nullability of the entity definition.

The MVP implementation may only contain checks for annotations present on fields.

Have an infrastructure for conveniently testing our defined rules against some sample code.

Spring Data Repositories only support the usage of their own org.springframework.lang.Nullable annotations¹. Misuses could lead to runtime errors when invoking repository methods and thus should be prevented.

By convention, the operand of the equals method should be nullable. In other words, a.equals(null) should be valid.

Currently, all of our rules run in a single composited arch rule, this is due to a lack of support from ArchUnit to run a collection of rules as separate tests. As a result, all rules are reported in a single violation message, and no "because" clause will be printed which is very less than ideal.

It would be great if we can have our own custom test runner that can generate tests for each rule, and also provide the source code location for each rule defined. This will be a huge user experience improvement when troubleshooting violations.

Modernizer is a fantastic maven plugin for checking legacy API calls. The plugin has many built-in rules that we can leverage.