When a widget has CONTENT_TEMPLATE: null, it ignores the contentBox attribute value passed via config. CONTENT_TEMPLATE is used to create a contentBox when one is not provided, and that by setting it
to NULL, I'm asking Widget not to create a contentBox when one is not provided.

I have just had the scenario where ordinarily, I would not want separate contentBox and boundingBox elements, but in this particular use case, it is required, but I find myself unable to override the
default contentBox by configuration.

I overrode _setCB to define the behaviour I expected.

_setCB: function(node) {

        var contentBox = Y.Node.one(node);

        if (!contentBox) {

            contentBox = (this.CONTENT_TEMPLATE === null) ? this.get(BOUNDING_BOX) : this._setBox(null, node, this.CONTENT_TEMPLATE);

        }

        return contentBox;

    },