MAGETWO-31363: [MPI] Unit and Integration tests coverage

Author: Pechenushko

app/code/Magento/OfflinePayments/Model/Observer.php

@@ -21,9 +21,7 @@ public function beforeOrderPaymentSave(\Magento\Framework\Event\Observer $observ
     {
         /** @var \Magento\Sales\Model\Order\Payment $payment */
         $payment = $observer->getEvent()->getPayment();
-        if ($payment->getMethod() ===
-            \Magento\OfflinePayments\Model\Banktransfer::PAYMENT_METHOD_BANKTRANSFER_CODE
-        ) {
+        if ($payment->getMethod() === Banktransfer::PAYMENT_METHOD_BANKTRANSFER_CODE) {
             $payment->setAdditionalInformation(
                 'instructions',
                 $payment->getMethodInstance()->getConfigData('instructions')