Nullable left off function type parameter with default value

[MK27]

This method signature:

open fun checkElement (
                elem: T,
                addFunc: ((elem: T) -> Unit)? = { dataList.add(it) }
        ) : Int

Is assessed by dokka 0.9.16 as:

open fun checkElement(elem: T, addFunc: (elem: T) -> Unit = { dataList.add(it) }): Int

When it should be:

open fun checkElement(elem: T, addFunc: ((elem: T) -> Unit)? = { dataList.add(it) }): Int

[KrystianUjma]

created PR for that #401