Suggestion by a customer, but in practice we cannot do it easily do to the lack of a standard Nonnull annotation. These are the ones that Kotlin detects:

• JetBrains (@Nullable and @NotNull from the org.jetbrains.annotations package)
• Android (com.android.annotations and android.support.annotations)
• JSR-305 (javax.annotation) // DEAD!
• FindBugs (edu.umd.cs.findbugs.annotations)
• Eclipse (org.eclipse.jdt.annotation)
• Lombok (lombok.NonNull).

None of these are reliable and standard enough to be used everywhere in our API's.
https://kotlinlang.org/docs/reference/java-interop.html#nullability-annotations

org.reflections:reflections does drag in com.google.code.findbugs:annotations, which contains javax.annotation.Nonnull, but it shouldn't do that and java 9 jigsaw will have a problem with that because it's a split package (which is illegal for module-info.java IIRC).