Scrollview inside constraint layout does not scroll to the bottom of the parent constraint

This layout works in my app.
The trick is to set these two attributes in ScrollView:
android:layout_height=”0dp”
app:layout_constraintBottom_toBottomOf=”parent”

The simplified layout from my app:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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"
    android:theme="@style/ThemeOverlay.AppCompat.Light">

    <RelativeLayout
        android:id="@+id/linear"
        android:layout_width="0dp"
        android:layout_height="56dp"
        android:background="@color/title"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <ScrollView
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@id/linear">

        <android.support.constraint.ConstraintLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <TextView
                android:id="@+id/titleView"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginLeft="8dp"
                android:layout_marginStart="8dp"
                android:text="@string/title"
                android:textSize="14sp"
                app:layout_constraintBaseline_toBaselineOf="@+id/title"
                app:layout_constraintLeft_toLeftOf="parent" />

            <EditText
                android:id="@+id/title"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_marginEnd="8dp"
                android:layout_marginRight="8dp"
                android:hint="toilet title"
                android:inputType="text"
                android:textColor="@android:color/holo_red_dark"
                android:textSize="12sp"
                app:layout_constraintLeft_toLeftOf="@+id/open_hour"
                app:layout_constraintLeft_toRightOf="@+id/titleView"
                app:layout_constraintRight_toRightOf="parent"
                app:layout_constraintTop_toTopOf="parent" />
            ...
            Other Views in ScrollView
            ...
        </android.support.constraint.ConstraintLayout>
    </ScrollView>
</android.support.constraint.ConstraintLayout>