title: Default values for attributes not available in theme
body: <p>I have defined custom attribute to use in my views:</p>
  
  <pre><code>&lt;attr name="customColor" format="color"/&gt;
  </code></pre>
  
  <p>And specified its value in my theme:</p>
  
  <pre><code>&lt;style name="AppTheme" parent="Theme.AppCompat.Light"&gt;
      &lt;!-- some other values --&gt;
      &lt;item name="customColor"&gt;#6d4c41&lt;/item&gt;
  &lt;/style&gt;
  </code></pre>
  
  <p>Now, I can use this attribute value in my view. Both in XML:</p>
  
  <pre><code>&lt;TextView
      android:textColor="?attr/customColor"
  /&gt;
  </code></pre>
  
  <p>and in code (Kotlin):</p>
  
  <pre><code>with(
      context.theme.obtainStyledAttributes(
          intArrayOf(R.attr.customColor)
      )
  ) {
      textColor = getColor(0, Color.parseColor("#ffffff"))
      recycle()
  }
  </code></pre>
  
  <p>(Java):</p>
  
  <pre><code>TypedArray a = context.getTheme().obtainStyledAttributes(
          new int[]{R.attr.customColor}
  );
  textColor = a.getColor(0, Color.parseColor("#ffffff"));
  a.recycle();
  </code></pre>
  
  <p>In case I <strong>forget to define</strong> the value in my theme, the code above will work fine, since I specified the default value. However, the XML will throw an exception when I try to inflate it.</p>
  
  <p>Is there a way to specify default attribute value for XML?</p>