Braintree\TransactionSearch::customerId PHP Method

    public static function customerId()
    {
        return new TextNode('customer_id');
    }

 /**
  * Get a collection of the entity's invoices.
  *
  * @param bool  $includePending
  * @param array $parameters
  *
  * @return \Illuminate\Support\Collection
  */
 public function invoices($includePending = false, $parameters = [])
 {
     $invoices = new Collection();
     $customer = $this->asBraintreeCustomer();
     $parameters = array_merge([TransactionSearch::customerId()->is($customer->id)], $parameters);
     $braintreeTransactions = Transaction::search($parameters);
     $subscriptionIds = [];
     foreach ($braintreeTransactions as $braintreeTransaction) {
         $subscriptionIds[] = $braintreeTransaction->subscriptionId;
     }
     $braintreeSubscriptions = BraintreeSubscription::fetch([], array_unique($subscriptionIds));
     // Here we will loop through the Braintree invoices and create our own custom Invoice
     // instances that have more helper methods and are generally more convenient to
     // work with than the plain Braintree objects are. Then, we'll return the array.
     if (!is_null($braintreeSubscriptions)) {
         foreach ($braintreeSubscriptions as $subscription) {
             if ($subscription->status == BraintreeSubscription::ACTIVE || $includePending) {
                 foreach ($subscription->transactions as $transaction) {
                     $invoices->push(new Invoice($this, $subscription, $transaction));
                 }
             }
         }
     }
     return $invoices->sortByDesc(function ($invoice) {
         return $invoice->date();
     });
 }