title: Unresolved reference on RecyclerView
body: <p>I'm able to retrieve the data from Firebase but when I try to load it into the groupie adapter, the recyclerview activity is not loading, and shows the following error "Unresolved reference: None of the following candidates are applicable because of receiver type mismatch....", I am I missing dependency??</p>
  
  <p>This is my activity code, under to the fetchUser method is where I get the error:</p>
  
  <pre><code>
  import android.os.Bundle
  import android.util.Log
  import androidx.appcompat.app.AppCompatActivity
  import com.google.firebase.database.DataSnapshot
  import com.google.firebase.database.DatabaseError
  import com.google.firebase.database.FirebaseDatabase
  import com.google.firebase.database.ValueEventListener
  import com.xwray.groupie.GroupAdapter
  import com.xwray.groupie.GroupieViewHolder
  import com.xwray.groupie.Item
  import kotlinx.android.synthetic.main.activity_new_message.*
  
  class NewMessageActivity : AppCompatActivity() {
  
      override fun onCreate(savedInstanceState: Bundle?) {
          super.onCreate(savedInstanceState)
          setContentView(R.layout.activity_new_message)
  
  
          // Activity screen title
          supportActionBar?.title = "Select User"
  
          val adapter = GroupAdapter&lt;GroupieViewHolder&gt;()
  
  
          adapter.add(UserItem())
          adapter.add(UserItem())
          adapter.add(UserItem())
  
          recycler_view_new_message.adapter = adapter
  
          fetchUsers()
  
      }
  }
  
  private fun fetchUsers() {
      val ref = FirebaseDatabase.getInstance().getReference("/users")
      ref.addListenerForSingleValueEvent(object: ValueEventListener {
  
          override fun onDataChange(p0: DataSnapshot) {
              val adapter = GroupAdapter&lt;GroupieViewHolder&gt;()
  
  
              p0.children.forEach {
                  Log.d("NewMessage", it.toString())
                  val user = it.getValue(User::class.java)
                  adapter.add(UserItem())
              }
              recycler_view_new_message.adapter = adapter /// THIS IS WHERE I GET THE UNRESOLVED REFERENCE ERROR
          }
  
          override fun onCancelled(p0: DatabaseError) {
  
          }
      })
  
  
  }
  
  class UserItem: Item&lt;GroupieViewHolder&gt;() {
      override fun bind(viewHolder: GroupieViewHolder, position: Int) {
      }
  
      override fun getLayout(): Int {
          return R.layout.user_row_new_message
      }
  
  }
  
  
  </code></pre>
  
  <p>This is the gradle dependencies:</p>
  
  <pre><code>    implementation fileTree(dir: 'libs', include: ['*.jar'])
      implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
      implementation 'androidx.appcompat:appcompat:1.0.2'
      implementation 'androidx.core:core-ktx:1.0.2'
      implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
      testImplementation 'junit:junit:4.12'
      androidTestImplementation 'androidx.test.ext:junit:1.1.0'
      androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.1'
  
      implementation 'com.google.firebase:firebase-analytics:17.2.0'
      implementation 'com.google.firebase:firebase-auth:19.2.0'
  
      implementation 'com.google.firebase:firebase-storage:19.1.0'
      implementation 'com.google.firebase:firebase-database:19.1.0'
      implementation 'de.hdodenhof:circleimageview:3.0.1'
      implementation 'androidx.recyclerview:recyclerview:1.1.0'
      implementation "com.xwray:groupie:2.7.0"
  
      implementation 'com.squareup.picasso:picasso:2.71828'
  
  
  }
  
  apply plugin: 'com.google.gms.google-services'
  </code></pre>
  
  <p>and this is my recyclerView XML config:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;androidx.constraintlayout.widget.ConstraintLayout
      xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"
      xmlns:tools="http://schemas.android.com/tools"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      tools:context=".NewMessageActivity"&gt;
  
      &lt;androidx.recyclerview.widget.RecyclerView
          android:id="@+id/recycler_view_new_message"
          android:layout_width="0dp"
          android:layout_height="0dp"
          app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
          app:layout_constraintBottom_toBottomOf="parent"
          app:layout_constraintEnd_toEndOf="parent"
          app:layout_constraintStart_toStartOf="parent"
          app:layout_constraintTop_toTopOf="parent" /&gt;
  
  
  &lt;/androidx.constraintlayout.widget.ConstraintLayout&gt;
  </code></pre>
  
  <p><strong>SOLUTION:</strong>
  It ended up being a very dumb mistake, I realized I had left fetchUsers() method outside of the NewMessageActivity class, so I just moved that method back into the class and I was able to reference the RecyclerView component.</p>