false-positive in AI_ANNOTATION_ISSUES_NEEDS_NULLABLE

[Vampire]

The following method triggers mentioned rule:

public Object foo() {
    return CompletableFuture.completedFuture(new Object()).join();
}

But this can never return null.
The only way join() can return null is, if the futuer actually computed to null.
But actually in this case the future cannot compute to null.
The real-life situation where I got this is a more complex future, but it also will not return null.