3.4.1阴影显示不出来

[xpx1003]

<androidx.constraintlayout.widget.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:id="@+id/main" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity">

<com.lihang.ShadowLayout
    android:id="@+id/mShadowLayout"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"
    app:hl_cornerRadius="10dp"
    app:hl_shadowColor="@color/black"
    app:hl_shadowLimit="10dp"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintStart_toStartOf="parent">

    <TextView
        android:id="@+id/txt_test"
        android:layout_width="wrap_content"
        android:layout_height="36dp"
        android:gravity="center"
        android:paddingLeft="10dp"
        android:paddingRight="10dp"
        android:text="圆角"
        android:textColor="#000" />
</com.lihang.ShadowLayout>

</androidx.constraintlayout.widget.ConstraintLayout>