Kotlin/Java-interop issue

This issue has been raised in the Kotlin issue tracker as well: https://youtrack.jetbrains.com/issue/KT-30925
For a detailed description and a zipped code example please review that ticket. I'm not sure if the problem is bad Kotlin Bytecode or a bug in Jersey's method scanner.
Short abstract of the problem:
This java interface
```java
@Path("/")
public interface Interface {
@GET
String myOperation(Boolean myFlag);
}
```
together with this Kotlin implementation:
```kotlin
class BrokenImplementation : Interface {
override fun myOperation(myFlag: Boolean) = "Hello World"
}
```
will compile, but lead to 404 errors. If I change the parameter to `myFlag: Boolean?`, it works.