Braintree\Customer::update PHP Method

    public static function update($customerId, $attributes)
    {
        return Configuration::gateway()->customer()->update($customerId, $attributes);
    }

 /**
  * Handle the event.
  *
  * @param  \Laravel\Spark\Events\Profile\ContactInformationUpdated  $event
  */
 public function handle($event)
 {
     if (!$event->user->hasBillingProvider()) {
         return;
     }
     BraintreeCustomer::update($event->user->braintree_id, ['email' => $event->user->email]);
 }