* If `toArray` is inherited from Java, it may take an argument or
return a value of a flexible type, which looks nullable in IR;
* The returned array may also have `out` variance of the type
argument;
* `Array<T>` is not the same as `Array<Any?>` if `T` is neither `Any`
nor `in Something`, so presence of `toArray(): Array<T>` does not
mean we don't need to generate a new `toArray`.
