NullPointerException at ResourceResolverFactory in AEM 6.1
<p>I am following this article to to automate uploading multiple images in AEM 6.1.</p>

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<p>At following line of <code>writeToClientLib</code> method of <code>HandleFile.java</code>, it throws <code>NullPointerException</code> when I try to upload images using client.</p>

<pre><code>ResourceResolver resourceResolver = resolverFactory.getAdministrativeResourceResolver(null);
</code></pre>