res/animator/heads_up_notification_transition_out.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  ~ Copyright (C) 2020 The Android Open Source Project
  ~
  ~ Licensed under the Apache License, Version 2.0 (the "License");
  ~ you may not use this file except in compliance with the License.
  ~ You may obtain a copy of the License at
  ~
  ~      http://www.apache.org/licenses/LICENSE-2.0
  ~
  ~ Unless required by applicable law or agreed to in writing, software
  ~ distributed under the License is distributed on an "AS IS" BASIS,
  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  ~ See the License for the specific language governing permissions and
  ~ limitations under the License.
  -->

<set xmlns:android="http://schemas.android.com/apk/res/android">
    <objectAnimator
        android:duration="@integer/headsup_exit_duration_ms"
        android:interpolator="@interpolator/heads_up_exit_direction_interpolator"
        android:propertyName="y"
        android:valueTo="0dp"
        android:valueType="floatType"/>
    <objectAnimator
        android:duration="@integer/headsup_exit_duration_ms"
        android:interpolator="@interpolator/heads_up_exit_alpha_interpolator"
        android:propertyName="alpha"
        android:valueTo="0.0"
        android:valueType="floatType"/>
</set>