title: Does pe:sheet support nested headers?
body: <p>I am using the PrimeFaces Extensions Sheet component in different contexts and I need different functionalities. I stumbled upon the requirement of nested headers. I see that the underlying component supports this, but I am not sure how to do it with the pe:sheet component.</p>
  
  <p>I already tried setting up the extender cfg property and also tried updating the hot instance, but it does not seem to work.</p>
  
  <pre><code>function sheetExtender(){
  this.cfg.colHeaders = true;
  this.cfg.rowHeaders = true;
  this.cfg.nestedHeaders: [
                      ["", {label:"my label", colspan:3}],
                      ["A", "B", "C", "D"]
                  ]
  </code></pre>
  
  <p>And also tried the following:</p>
  
  <pre><code>PF('widgetName').ht.updateSettings({
  colHeaders: true,
  rowHeaders: true,
  nestedHeaders: [
  ["", {label:"my label", colspan:3}],
  ["A", "B", "C", "D"]
  ]
  })
  </code></pre>
  
  <p>I was hoping that one of these approaches would trigger the underlying HandsonTable component to draw nested headers. If non of these work, what would be a workaround for it?</p>