Braintree\CustomerGateway::createSignature PHP Method

    public static function createSignature()
    {
        $creditCardSignature = CreditCardGateway::createSignature();
        unset($creditCardSignature[array_search('customerId', $creditCardSignature)]);
        $signature = ['id', 'company', 'email', 'fax', 'firstName', 'lastName', 'phone', 'website', 'deviceData', 'deviceSessionId', 'fraudMerchantId', 'paymentMethodNonce', ['riskData' => ['customerBrowser', 'customerIp', 'customer_browser', 'customer_ip']], ['creditCard' => $creditCardSignature], ['customFields' => ['_anyKey_']]];
        return $signature;
    }

 public function testCreateSignature_doesNotIncludeCustomerIdOnCreditCard()
 {
     $signature = Braintree\CustomerGateway::createSignature();
     $creditCardSignatures = array_filter($signature, 'Test\\Unit\\CustomerTest::findCreditCardArray');
     $creditCardSignature = array_shift($creditCardSignatures)['creditCard'];
     $this->assertNotContains('customerId', $creditCardSignature);
 }