Google Drive Java API V3 delete custom property
<p>I'm using the Google Drive API for Java with a service account and I want to delete costume properties which were set by myself. </p>

<p>At <a href="https://developers.google.com/drive/v3/web/migration" rel="nofollow noreferrer">https://developers.google.com/drive/v3/web/migration</a> I read that I need to update the file with a map where I put the key with a null value. </p>

<p><code>(files.update with {'properties':{'key':null}})</code></p>

<p>my code looks like this: </p>

<pre><code>File body = new File();
Map&lt;String, String&gt; map = new HashMap&lt;&gt;();
map.put(propertyName, null);
body.setProperties(map);
service.files().update(fileId, body).execute();
</code></pre>

<p>The JSON content is <code>{properties={test=null}}</code></p>

<p>The above code works without any exception, but the property is still set. How can I delete the property? </p>