All package-info.java files must include both @NonNullApi and @NonNullFields annotations to establish null-safety at the package level. These annotations must each be on a single line for proper detection by static analysis tools. This practice makes null-handling behavior explicit, reduces NullPointerExceptions, and enforces consistent null-safety conventions across the codebase. Example: ```java /** * Package documentation here. */ @NonNullApi @NonNullFields package com.example.mypackage; import org.springframework.lang.NonNullApi; import org.springframework.lang.NonNullFields; ```