title: Cardview not displaying in android studio 3.5.1
body: <p>I have tried <code>CardView</code> library on the older android studio version 3.3.1 and the code was working. The emulator was displaying the correct images. But, I switched to the new version 3.5 nothing is displaying in the <code>CardView</code>, not even a <code>TextView</code>. </p>
  
  <p>xml code: </p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout
      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:orientation="vertical"
      android:padding="10dp"
      android:background="#fcfcfc"
      android:gravity="center"
      android:id="@+id/LinearLayout1"&gt;
  
      &lt;!-- A CardView that contains a TextView --&gt;
      &lt;android.support.v7.widget.CardView
          xmlns:card_view="http://schemas.android.com/apk/res-auto"
          android:id="@+id/card_view"
          android:layout_gravity="center"
          android:layout_width="200dp"
          android:layout_height="200dp"
          card_view:cardCornerRadius="4dp"&gt;
  
          &lt;TextView
              android:id="@+id/info_text"
              android:layout_width="match_parent"
              android:layout_height="match_parent" /&gt;
      &lt;/android.support.v7.widget.CardView&gt;
  
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>Gradle:</p>
  
  <pre><code>dependencies {
  
  implementation fileTree(dir: 'libs', include: ['*.jar'])
  implementation 'androidx.appcompat:appcompat:1.1.0'
  implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
  testImplementation 'junit:junit:4.12'
  androidTestImplementation 'androidx.test:runner:1.2.0'
  androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
  implementation 'com.android.support:cardview-v7:28.0.0'
  
  }
  </code></pre>