title: amcharts_Child tree should not open untill clicked
body: <p>How to make child trees open on click? When we click the parent node A it opens its all child and sub-child trees. </p>
  
  <p>It should open the sub-child on click. Like when click on A, it should not open A21 which is sub-child of A2.</p>
  
  <p><a href="https://i.stack.imgur.com/Wgc1E.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Wgc1E.png" alt="amchart"></a></p>
  
  <p>JS Code is following </p>
  
  <pre><code>/**
   * Documentation is available at:
   * https://www.amcharts.com/docs/v4/
   */
  
  am4core.useTheme(am4themes_animated);
  
  // Create chart
  var chart = am4core.create("chartdiv", am4plugins_forceDirected.ForceDirectedTree);
  
  // Create series
  var series = chart.series.push(new am4plugins_forceDirected.ForceDirectedSeries());
  
  // Set data
  series.data = [{"name": "A",
    "children": [{
      "name": "A1",
      "value": 1,
    }, {
      "name": "A2","value": 1,
      "children": [{
      "name": "A21",
      "value": 1,
    }]
    }, 
                 {
      "name": "A3",
      "value": 1,
      }]
  }];
  
  // Set up data fields
  series.dataFields.value = "value";
  series.dataFields.name = "name";
  series.dataFields.id = "id";
  series.dataFields.children = "children";
  series.dataFields.linkWith = "link";
  // Add labels
  series.nodes.template.label.text = "{name}";
  series.nodes.template.label.valign = "center";
  series.nodes.template.label.fill=am4core.color("#000");
  series.nodes.template.label.dy = 10;
  series.fontSize = 12;
  series.minRadius = 30;
  series.maxRadius = 30;
  
  // Configure circles
  series.nodes.template.circle.fillOpacity = 0.5;
  
  </code></pre>
  
  <p>HTML Scripts</p>
  
  <pre><code>&lt;script src="//www.amcharts.com/lib/4/core.js"&gt;&lt;/script&gt;
  &lt;script src="//www.amcharts.com/lib/4/charts.js"&gt;&lt;/script&gt;
  &lt;script src="//www.amcharts.com/lib/4/themes/animated.js"&gt;&lt;/script&gt;
  &lt;script src="//www.amcharts.com/lib/4/themes/dataviz.js"&gt;&lt;/script&gt;
  &lt;script src="//www.amcharts.com/lib/4/plugins/forceDirected.js"&gt;&lt;/script&gt;
  &lt;div id="chartdiv"&gt;&lt;/div&gt;
  </code></pre>