title: Searching array of objects with subarrays
body: <p>I have an object called Topic of which model is:</p>
  
  <pre><code>Topic
   - title (String)
   - subTopics (Array of Topics)
   - parentTopic (Topic)
  </code></pre>
  
  <p>Sample data:</p>
  
  <pre><code>Chapter 0
  Chapter 1
   - Topic 1.1
   - Topic 1.2
     - Topic 1.2.1
     - Topic 1.2.2
       - Topic 1.2.2.1
       - Topic 1.2.2.2
  </code></pre>
  
  <p>How can I search for the Topic "<strong>Topic 1.2.2.2</strong>" using a predicate?</p>