Original link: Spring Framework 7 / LinkedIn / Sebastien Deleuze.
Java does not support non nullable reference types unlike many similar languages (Kotlin, C# from version 8.0).
But there are various annotations to help with the problem. One of them is JSpecify. And Spring from version 7.0 will have JSpecify annotations for null safety.
The short version is that @NullMarked on package or class inform that default is non nullable and @Nullable on fields/method parameters/method return type inform that it is nullable.