title: select/unselect all elements in one go in primefaces <p:selectCheckboxMenu>?
body: <p>I have gone through the documentation of primefaces and sadly there is no option to select all the options of the <code>p:selectCheckboxMenu</code> component in one go like you can using Javascript. </p>
  
  <p>Can anyone suggest how it can be done using Javascript or using the Backing Bean?</p>