`@Nullable` and `Nonnull` VS jspecify

[jspecify](https://jspecify.dev/) is more popular and gets better community tools support today, the next Spring 7.0 has already migrated to jspecify to check the field/method parameter/return type nullable.

In the current Jakarta Annotations, the `@Nullable` and `NonNull` are extracted from JSR305. Jspecify provides more features and compatibility.

With wider tool support when using Jspecify, we can generate static analysis reports at compile time。

If we keep the existing `@Nullable/@Nonnull` in Jakarta EE, can we generate analysis results at build/deployment time?

Start with the jspecify link and the current Jakarta Annotations discussion of @Nullable and @Nonnull. Compare the stated Spring 7.0 migration and available tool support, then determine whether the project should adopt jspecify or support build/deployment-time analysis while retaining the existing annotations. Done requires a documented decision and defined scope.

Written by the indexing model from the issue text.