Null Safety (Boot 3 / Framework 6)

Use the nullability model supported by the project. Spring Framework 6 commonly uses org.springframework.lang.Nullable, @NonNull, and package-level @NonNullApi. JSpecify can be introduced deliberately, but do not assume Framework 7 migration semantics in a Boot 3 module.

@NonNullApi
package com.example.orders;

import org.springframework.lang.NonNullApi;

Annotate genuine nullable results and parameters with @Nullable. Keep repository return types explicit, validate external input at boundaries, and use Kotlin compiler settings that match the annotations when Java and Kotlin are mixed. If the project standardizes JSpecify independently, apply it consistently at module boundaries and document the chosen checker.

Gotchas