Cleanest way to insert Java/KDoc above the method or class

I'm developing a plugin, that is capable of creating KDoc/Javadoc comments for given methods and classes, that supports both Java/Kotlin. The tricky part is that as far as I got there is no clean way to support such a technique using the UAST library only, so I'm operating around `PsiElements`, to be able to use the `.addBefore` method. It looks like that:

private fun insertDocumentation(element: PsiElement, documentation: String) {
   val factory = JavaPsiFacade.getElementFactory(element.project)
   val documentationElement = factory.createDocCommentFromText(documentation, element)

   WriteCommandAction.runWriteCommandAction(element.project) {
      // Distinguish between class elements and others to correctly position the documentation.
      val createdDoc = if (element is PsiClass) {
         element.addBefore(documentationElement, element.firstChild)
      } else {
         element.parent.addBefore(documentationElement, element)
      }

      // Formatting the code after adding the documentation.
      CodeStyleManager
         .getInstance(element.project)
         .reformat(createdDoc.containingFile)
   }
}

And it works perfectly with java classes, but for some reason, it's unable to correctly insert a comment for kotlin classes, that perform like this (end of KDoc and class declaration is on the same line, and not being reformated afterall!):

/**
* A class representing a calculator that can perform basic arithmetic operations.
*/class Calculator {

Whitespace insertion is not recommended, there is no way to execute ::addBefore on UElement, is there any clean way to paste a kotlin documentation for a class?