title: Values passed to <include> layout is not displayed
body: <p>I have a included an  layout and passing data using app:variable-name but cannot see the results. The variable-name is defined in the layout to be included. Do the way I pass data to the layout incorrect?</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;layout
      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" &gt;
          &lt;LinearLayout
              android:layout_width="match_parent" 
              android:layout_height="match_parent"
              android:orientation="vertical"
              tools:context=".AboutFragment"&gt;
  
              &lt;include
                  android:id="@+id/dev1"
                  layout="@layout/include_dev_credit"
                  app:pic="@{@drawable/dev1}"
                  app:name="@{@string/dev1}"
                  app:role="@{@string/dev1}"
              /&gt;
  
      &lt;/LinearLayout&gt;
  &lt;/layout&gt;
  </code></pre>
  
  <p>This is is the layout to be included. It contains one imageview and two text views to be inflated. The data variables have been defined here.</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;layout
          xmlns:android="http://schemas.android.com/apk/res/android"
          xmlns:app="http://schemas.android.com/apk/res-auto"
  &gt;
  
      &lt;data&gt;
  
          &lt;variable
                  name="name"
                  type="String"/&gt;
  
          &lt;variable
                  name="role"
                  type="String"/&gt;
  
          &lt;variable
                  name="pic"
                  type="android.graphics.drawable.Drawable"/&gt;
  
      &lt;/data&gt;
  
      &lt;androidx.constraintlayout.widget.ConstraintLayout
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_gravity="center_horizontal" android:paddingBottom="8dp"&gt;
  
              &lt;ImageView
                      android:layout_width="100dp"
                      android:layout_height="100dp"
                      android:layout_gravity="center"
                      android:scaleType="centerCrop"
                      android:src="@{pic}"/&gt;
  
          &lt;TextView
                  android:id="@+id/nameView"
                  android:layout_width="wrap_content"
                  android:layout_height="wrap_content"
                  android:layout_marginStart="16dp"
                  android:layout_marginTop="16dp"
                  android:layout_marginEnd="16dp"
                  android:paddingTop="8dp"
                  android:text="@{name}"
                  android:ems="8"
                  android:textAlignment="center"
                  android:textAppearance="@style/TextAppearance.AppCompat.Large"
                  app:layout_constraintEnd_toEndOf="parent"
                  app:layout_constraintHorizontal_bias="0.5"
                  app:layout_constraintStart_toEndOf="@+id/picView"
                  app:layout_constraintTop_toTopOf="parent"/&gt;
  
          &lt;TextView
                  android:id="@+id/roleView"
                  android:layout_width="wrap_content"
                  android:layout_height="wrap_content"
                  android:layout_marginStart="16dp"
                  android:layout_marginTop="4dp"
                  android:layout_marginEnd="16dp"
                  android:ems="10"
                  android:textAlignment="center"
                  android:text="@{role}"
                  android:textAppearance="@style/TextAppearance.AppCompat.Medium"
                  app:layout_constraintEnd_to`enter code here`EndOf="parent"
                  app:layout_constraintStart_toEndOf="@+id/picView"
                  app:layout_constraintTop_toBottomOf="@+id/nameView"/&gt;
  
      &lt;/androidx.constraintlayout.widget.ConstraintLayout&gt;
  &lt;/layout&gt;
  </code></pre>