title: Unresolved reference arraylist : java.util vs kotlin.collections import issue
body: <p>ArrayList in the below code gives unresolved reference. The IDE recommends
  possible import solution import of java.util.arraylist. This does not resolve the issue.</p>
  <p>I checked the source website code and  kotlin.collections arraylist import will fix the issue. Somehow the latter import is not showing up in project files.</p>
  <p>What import library am I missing? Only java dependency is being shown in the autocomplete and kotlin one is missing. The source github url is linked below for build.gradle file if needed.</p>
  <p>CharactersAdapter.kt</p>
  <pre><code>class CharactersAdapter(private val listener: CharacterItemListener) : RecyclerView.Adapter&lt;CharacterViewHolder&gt;() {
  
      interface CharacterItemListener {
          fun onClickedCharacter(characterId: Int)
      }
  
      private val items = ArrayList&lt;Character&gt;()
  
      fun setItems(items: ArrayList&lt;Character&gt;) {
          this.items.clear()
          this.items.addAll(items)
          notifyDataSetChanged()
      }
  </code></pre>
  <p><a href="https://github.com/sberoch/RickAndMorty-AndroidArchitectureSample" rel="nofollow noreferrer">https://github.com/sberoch/RickAndMorty-AndroidArchitectureSample</a></p>