Package-scope non-null annotation in Java for Kotlin (built by Gradle)

Question

I'm trying to write a Java library that has a non-nullable API, and I'd like Kotlin to properly infer this non-nullability. I'm using JSR-305 annotations and its @TypeQualifierDefault to achieve the effect for the entire package, as per Kotlin's Java interop reference.

I build it all using Gradle 4.10.2 and I supply -Xjsr305=strict to the Kotlin compiler, as instructed. Yet, when I reflectively inspect the types from Kotlin, they are reported as platform types, e.g.:

fun sample.Foo.bar(T!): kotlin.collections.(Mutable)List<T!>!

What am I doing wrong that I don't get the following output?

fun sample.Foo.bar(T): kotlin.collections.(Mutable)List<T>

Note that Spring Framework 5 has a similar annotation named @NonNullApi.

I'm using OpenJDK 11.

PS. I know I can just annotate every method and parameter with @Nonnull, but I'm after global behavior and converting Kotlin's List<T!> to List<T>.

---

Here's the MCVE:

• src/main/java/sampleAnnotation/NonNullPackage.java

  package sampleAnnotation;
  
  import javax.annotation.Nonnull;
  import javax.annotation.meta.TypeQualifierDefault;
  import java.lang.annotation.*;
  
  @Nonnull
  @Retention(RetentionPolicy.RUNTIME)
  @Target(ElementType.PACKAGE)
  @TypeQualifierDefault({
          ElementType.FIELD, ElementType.METHOD, ElementType.PARAMETER, ElementType.TYPE_USE
  })
  public @interface NonNullPackage {
  }
  

• src/main/java/foo/package-info.java

  @NonNullPackage
  package foo;
  
  import sampleAnnotation.NonNullPackage;
  

• src/main/java/foo/Foo.java

  package foo;
  
  import java.util.List;
  
  public interface Foo {
      <T> List<T> bar(T t);
  }
  

• src/main/kotlin/sampleKotlin/Main.kt

  package sampleKotlin
  
  import foo.Foo
  import kotlin.reflect.full.memberFunctions
  
  fun main(args : Array<String>) {
      println(Foo::class.memberFunctions.first())
  }
  

• build.gradle

  plugins {
      id 'java'
      id 'org.jetbrains.kotlin.jvm' version '1.3.0'
  }
  
  wrapper {
      gradleVersion = '4.10.2'
  }
  
  repositories {
      mavenCentral()
  }
  
  dependencies {
      compileOnly group: 'com.google.code.findbugs', name: 'jsr305', version: '3.0.2'
  
      compile group: 'org.jetbrains.kotlin', name: 'kotlin-stdlib'
      compile group: 'org.jetbrains.kotlin', name: 'kotlin-reflect'
  }
  
  compileKotlin {
      kotlinOptions.freeCompilerArgs = ['-Xjsr305=strict']
  }