title: Parent-Child Checkbox in Material Checkbox
body: <p>I have two cases that I want to implement:</p>
  
  <pre><code>[]Checkbox1
      []checkbox1.1
      []checkbox1.2
  </code></pre>
  
  <ol>
  <li>If I select parent node checkbox1 it should not select it's children.</li>
  <li>If I select both the child, it should not select parent.</li>
  </ol>
  
  <p>I am using mat checkboxes, any idea how it can be achieved. </p>