title: Margin doesn't work on a side without any constraint in ConstraintLayout
body: <p>I have an ImageView in a ConstraintLayout whose id is "thumbnail" in the XML below. I want it to be aligned top left of its parent and have a 8dp margin at bottom. However, bottom margin is not applied since there is no constraint on that side. I don't connect its bottom to its parent because it gets centered, which I don't want.</p>
  
  <p>Is there any way to solve this? Like to be able align it to the top when bottom constraint is provided?</p>
  
  <pre><code>&lt;androidx.constraintlayout.widget.ConstraintLayout
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:clickable="true"
      android:focusable="true"&gt;
  
      &lt;androidx.appcompat.widget.AppCompatImageView
          android:id="@+id/thumbnail"
          android:layout_width="56dp"
          android:layout_height="56dp"
          android:layout_marginTop="8dp"
          android:layout_marginBottom="8dp"
          android:scaleType="centerCrop"
          app:layout_constraintDimensionRatio="1:1"
          app:layout_constraintStart_toStartOf="parent"
          app:layout_constraintTop_toTopOf="parent"
          app:srcCompat="@drawable/bg_track_artwork" /&gt;
  
      &lt;TextView
          android:id="@+id/title"
          android:layout_width="0dp"
          android:layout_height="wrap_content"
          android:layout_marginStart="@dimen/margin"
          android:text="Title"
          android:textColor="#040404"
          android:textSize="15sp"
          android:textStyle="bold"
          android:typeface="sans"
          app:firstBaselineToTopHeight="32dp"
          app:layout_constraintBottom_toTopOf="@+id/subtitle"
          app:layout_constraintEnd_toStartOf="@+id/itemMenu"
          app:layout_constraintStart_toEndOf="@+id/thumbnail"
          app:layout_constraintTop_toTopOf="parent" /&gt;
  
      &lt;TextView
          android:id="@+id/subtitle"
          android:layout_width="0dp"
          android:layout_height="wrap_content"
          android:text="Subtitle"
          android:textSize="10sp"
          app:firstBaselineToTopHeight="20dp"
          app:layout_constraintEnd_toEndOf="@+id/title"
          app:layout_constraintStart_toStartOf="@+id/title"
          app:layout_constraintTop_toBottomOf="@+id/title" /&gt;
  
      &lt;LinearLayout
          android:id="@+id/itemMenu"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:layout_marginStart="@dimen/quarter_margin"
          android:orientation="horizontal"
          app:layout_constraintEnd_toEndOf="parent"
          app:layout_constraintStart_toEndOf="@+id/title"
          app:layout_constraintTop_toTopOf="parent"&gt;
  
          &lt;androidx.appcompat.widget.AppCompatImageView
              android:id="@+id/overflowIcon"
              android:layout_width="@dimen/icon_width"
              android:layout_height="@dimen/icon_height"
              android:padding="@dimen/icon_padding"
              app:srcCompat="@drawable/ic_more"
              app:tint="@color/icon_gray_light" /&gt;
  
      &lt;/LinearLayout&gt;
  
  &lt;/androidx.constraintlayout.widget.ConstraintLayout&gt;
  </code></pre>