title: How to create tree view inside the dropdown using angular material?
body: <p>Can anyone tell me, how to create a tree view inside the drop down. The drop down values will be getting from rest api call as json as follows. And subchild may contains one more level of child as well.</p>
  <p>I have to do auto suggestion here to perform the filter from parent as well as the child level too.</p>
  <pre><code> VehicleList = [
        {
          parent: &quot;audi&quot;,
          child: [{
            type: 'G-audiA',
            subchild: [{
                id: 1,
                name: 'type audi A1'
            }, {
                id: 2,
                name: 'type audi A2'
            }]
          }, {
            type: 'G-audiB',
            subchild: [{
                id: 1,
                name: 'type audi B1'
            }, {
                id: 2,
                name: 'type audi B2'
            }]
          }]
        }, {
          parent: &quot;bmw&quot;,
          child: [{
            type: 'G-bmwA',
            subchild: [{
                id: 1,
                name: 'type bmw A1'
            }, {
                id: 2,
                name: 'type bmw A2'
            }]
          }, {
            type: 'G-bmwB',
            subchild: [{
                id: 1,
                name: 'type bmw B1'
            }, {
                id: 2,
                name: 'type bmw B2'
            }]
          }]
    }]
  </code></pre>
  <p>Anyone help will be appreciated!!!</p>