title: What does CQ5's Placeholder.getDefaultPlaceholder exactly do?
body: <p>The <a href="http://bit.ly/1lhUyVK" rel="nofollow">API docs</a> are not much descriptive:</p>
  
  <blockquote>
    <p>Get default placeholder for any component incl. title as text information</p>
  </blockquote>
  
  <p>Here's the method signature:</p>
  
  <pre><code>public static String getDefaultPlaceholder(ServletRequest slingRequest,
                                             Component component,
                                             String defaultPlaceholder)
  </code></pre>
  
  <ol>
  <li>What's a Placeholder? What is/should be returned by <code>getDefaultPlaceholder</code>?</li>
  <li>What's the purpose of <code>defaultPlaceholder</code>? What should I pass as <code>defaultPlaceholder</code>? What would happen if I pass <code>null</code>?</li>
  </ol>