test.kt

package com.unuuu.bookkeeper.view.adapter

...

class ExampleAdapter(context: Context) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {

    ...
    private val inflater: LayoutInflater = LayoutInflater.from(context)

    private class CommentViewHolder(view: View) : RecyclerView.ViewHolder(view) {
        fun initialize(comment: Comment) {
            comment.subComment.forEach {
              // viewをLayoutInflatorを使ってxmlから生成する
              val subView = inflater.inflate(R.layout.adapter_example_row_sub_comment, viewGroup, false)
              subView.initialize(it)
              view.comemntLayout.addView(subView)
            }
            ...
        }
    }
}