Visual Composer class extends namespace issue

An Answer

I’ve had an answer to this question over on StackOverflow.

The Given Solution:

namespace Roots\Sage\VisualComposer {
  ...    
}

...

namespace {
  // global code
  if ( class_exists( '\\WPBakeryShortCodesContainer' ) ) {
    class WPBakeryShortCode_Your_Gallery extends \WPBakeryShortCodesContainer {}
  }
}

Simple.