Spinner dropdown outer border
<p>How do you set border for entire dropdown and not for items itself? </p>

<p><strong>Expectation</strong>:</p>

<p>Perhaps its not clearly seen but I'm interested in that white border outside entire dropdown. See red note</p>

<p><a href="https://i.stack.imgur.com/tKwJQ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/tKwJQ.png" alt="enter image description here"></a></p>

<p><strong>Reality</strong>:</p>

<p><a href="https://i.stack.imgur.com/Ztdzw.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Ztdzw.png" alt="enter image description here"></a></p>

<p>spinner_item.xml:</p>

<pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
&lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/primary_blue_dark"&gt;

    &lt;TextView
        android:id="@+id/tv_spinner_item"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingLeft="12dp"
        android:gravity="center_vertical|start"
        style="@style/sp_squared_style"/&gt;

    &lt;ImageView
        android:id="@+id/iv_underline"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginRight="12dp"
        android:layout_marginLeft="12dp"
        android:layout_marginBottom="6dp"
        android:background="@drawable/ic_underline"/&gt;
&lt;/LinearLayout&gt;
</code></pre>