Constraint Layout DOJO - Solution (STEP 3)

group_retweet.xml

<android.support.constraint.Group
    android:id="@+id/group_retweet"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    app:constraint_referenced_ids="retweet_top, retweet_user"/>

profile_image.xml

<de.hdodenhof.circleimageview.CircleImageView
    android:id="@+id/profile_image"
    android:layout_width="50dp"
    android:layout_height="50dp"
    android:layout_marginTop="8dp"

    android:src="@drawable/profile_image"

    app:layout_constraintTop_toBottomOf="@+id/retweet_top"
    app:layout_constraintLeft_toLeftOf="parent"/>

retweet_top.xml

<ImageView
    android:id="@+id/retweet_top"
    android:layout_width="15dp"
    android:layout_height="15dp"

    android:src="@drawable/ic_retweet"
    android:tint="@color/gray"

    app:layout_constraintTop_toTopOf="@+id/retweet_user"
    app:layout_constraintBottom_toBottomOf="@+id/retweet_user"
    app:layout_constraintRight_toRightOf="@id/profile_image"/>

retweet_user.xml

<TextView
    android:id="@+id/retweet_user"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    tools:text="Nicolas Roard retweetou"
    android:textColor="@color/gray"

    app:layout_constraintTop_toTopOf="@id/retweet_top"
    app:layout_constraintLeft_toLeftOf="@+id/username"/>