Need to set appbarlayout elevation to 1dp

fragment_replies.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout ... 
    >

  <android.support.design.widget.CoordinatorLayout
      ...
      >

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        >
        <!--
          app:elevation="1dp" remove elevation entirely, 
          but without it elevation is default -->
      <include layout="@layout/toolbar_center_title" />
      
    </android.support.design.widget.AppBarLayout>

    <RecyclerView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        ...
        />
  </android.support.design.widget.CoordinatorLayout>

  <android.support.v7.widget.CardView
      android:id="@+id/input_wrapper"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_alignParentBottom="true"
      ...
      >
      ...
      </android.support.v7.widget.CardView>
</RelativeLayout>

toolbar_center_title.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/toolbar"
    android:layout_width="match_parent"
    android:layout_height="?attr/actionBarSize"
    android:background="@android:color/white"
    android:elevation="1dp"
    app:elevation="1dp"
    app:layout_scrollFlags="scroll">
    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_margin="12dp">
        <TextView
            android:id="@+id/toolbar_title"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:maxLines="1"
            android:maxLength="30"
            android:ellipsize="end"
            android:textColor="@android:color/black"
            style="@style/TextAppearance.Widget.AppCompat.Toolbar.Title" />
        <ImageView
            android:id="@+id/check_mark"
            android:visibility="gone"
            android:src="@drawable/ic_verify"
            android:layout_toRightOf="@+id/toolbar_title"
            android:layout_alignBottom="@id/toolbar_title"
            android:layout_alignTop="@id/toolbar_title"
            android:layout_marginLeft="2dp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
    </RelativeLayout>
</android.support.v7.widget.Toolbar>