title: MotionLayout with vertical ScrollView
body: <p>I'm trying to make animation with motion layout, and want to set scrollView as targetAnchor for motion scene onSwipe Transition, but it doesn't work. 
  Maybe I don't know some thing about onSwipe transition.</p>
  
  <p>Here is my layout file </p>
  
  <pre class="lang-xml prettyprint-override"><code>    &lt;androidx.constraintlayout.motion.widget.MotionLayout xmlns:android="http://schemas.android.com/apk/res/android"
          xmlns:app="http://schemas.android.com/apk/res-auto"
          android:layout_width="match_parent"
          android:layout_height="match_parent"
          android:background="@color/main_background_color"
          app:layoutDescription="@xml/base_scroll_scene"&gt;
  
          &lt;ImageView
              android:id="@+id/background_image"
              android:layout_width="0dp"
              android:layout_height="0dp"
              android:layout_marginBottom="@dimen/scrollable_background_image_margin_bottom"
              android:scaleType="centerCrop"
              android:src="@drawable/lift_bg"
              app:layout_constraintBottom_toBottomOf="parent"
              app:layout_constraintEnd_toEndOf="parent"
              app:layout_constraintStart_toStartOf="parent"
              app:layout_constraintTop_toTopOf="parent" /&gt;
  
          &lt;FrameLayout
              android:layout_width="match_parent"
              android:layout_height="@dimen/top_gradient_mask_height"
              android:background="@drawable/top_gradient_mask"
              app:layout_constraintStart_toStartOf="parent"
              app:layout_constraintTop_toTopOf="parent" /&gt;
  
          &lt;ImageView
              android:id="@+id/ski_more_logo"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:layout_marginTop="@dimen/ski_more_logo_margin_top"
              android:src="@drawable/ic_skimore_logo"
              app:layout_constraintEnd_toEndOf="parent"
              app:layout_constraintStart_toStartOf="parent"
              app:layout_constraintTop_toTopOf="parent" /&gt;
  
          &lt;ImageView
              android:id="@+id/locked_icon"
              android:layout_width="32dp"
              android:layout_height="32dp"
              android:layout_marginTop="@dimen/locked_icon_margin_top"
              android:src="@drawable/ic_lock"
              app:layout_constraintEnd_toEndOf="parent"
              app:layout_constraintStart_toStartOf="parent"
              app:layout_constraintTop_toBottomOf="@+id/ski_more_logo" /&gt;
  
          &lt;FrameLayout
              android:id="@+id/bottom_gradient_mask"
              android:layout_width="match_parent"
              android:layout_height="0dp"
              android:background="@drawable/bottom_gradient_mask"
              app:layout_constraintBottom_toBottomOf="@+id/background_image" /&gt;
  
          &lt;ScrollView
              android:id="@+id/content_scroll_view"
              android:layout_width="match_parent"
              android:layout_height="0dp"
              android:overScrollMode="never"
              app:layout_constraintBottom_toBottomOf="parent"
              app:layout_constraintTop_toTopOf="parent"&gt;
  
  
              &lt;FrameLayout
                  android:id="@+id/content_container_view"
                  android:layout_width="match_parent"
                  android:clickable="false"
                  android:layout_height="match_parent" /&gt;
  
  
          &lt;/ScrollView&gt;
      &lt;/androidx.constraintlayout.motion.widget.MotionLayout&gt;
  </code></pre>
  
  <p>In scroll view programmatically i'm adding some content with big height, which will be scrollable.</p>
  
  <p>And here is my motion scene </p>
  
  <pre class="lang-xml prettyprint-override"><code>&lt;MotionScene xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:motion="http://schemas.android.com/apk/res-auto"&gt;
      &lt;Transition
          motion:constraintSetEnd="@+id/end"
          motion:constraintSetStart="@+id/start"
          motion:duration="1000"&gt;
          &lt;OnSwipe
              motion:dragDirection="dragUp"
              motion:touchAnchorId="@+id/content_scroll_view"
              motion:touchAnchorSide="top" /&gt;
      &lt;/Transition&gt;
  
      &lt;ConstraintSet android:id="@+id/start"/&gt;
      &lt;ConstraintSet android:id="@+id/end"&gt;
          &lt;Constraint
              android:id="@+id/background_image"
              android:layout_width="0dp"
              android:layout_height="@dimen/top_gradient_mask_height"
              android:layout_marginBottom="@dimen/scrollable_background_image_margin_bottom"
              android:scaleType="centerCrop"
              android:src="@drawable/lift_bg"
              motion:layout_constraintEnd_toEndOf="parent"
              motion:layout_constraintStart_toStartOf="parent"
              motion:layout_constraintTop_toTopOf="parent" /&gt;
  
      &lt;/ConstraintSet&gt;
  
  &lt;/MotionScene&gt;
  </code></pre>
  
  <p>Please help me, Thanks.</p>