MAGETWO-33060: Refactor __() to return Phrase object

- DataObjectProcessor->buildOutputDataArray() updated;
- Configurable->getSpecifyOptionMessage() modified;
- Integration SaveRatesTest updated;

Author: Dmytro Poperechnyy

app/code/Magento/ConfigurableProduct/Model/Product/Type/Configurable.php

@@ -847,7 +847,7 @@ public function checkProductBuyState($product)
      */
     public function getSpecifyOptionMessage()
     {
-        return __('Please specify the product\'s option(s).');
+        return (string)__('Please specify the product\'s option(s).');
     }
 
     /**

dev/tests/integration/testsuite/Magento/CurrencySymbol/Controller/Adminhtml/System/Currency/SaveRatesTest.php

@@ -52,7 +52,7 @@ public function testSaveAction()
         $this->dispatch('backend/admin/system_currency/saveRates');
 
         $this->assertSessionMessages(
-            $this->contains(__('All valid rates have been saved.')),
+            $this->contains((string)__('All valid rates have been saved.')),
             \Magento\Framework\Message\MessageInterface::TYPE_SUCCESS
         );
 
@@ -84,7 +84,7 @@ public function testSaveWithWarningAction()
         $this->dispatch('backend/admin/system_currency/saveRates');
 
         $this->assertSessionMessages(
-            $this->contains(__('Please correct the input data for %1 => %2 rate', $currencyCode, $currencyTo)),
+            $this->contains((string)__('Please correct the input data for %1 => %2 rate', $currencyCode, $currencyTo)),
             \Magento\Framework\Message\MessageInterface::TYPE_WARNING
         );
     }

lib/internal/Magento/Framework/Reflection/DataObjectProcessor.php

@@ -116,7 +116,7 @@ public function buildOutputDataArray($dataObject, $dataObjectType)
                     $valueResult = [];
                     $arrayElementType = substr($returnType, 0, -2);
                     foreach ($value as $singleValue) {
-                        if (is_object($singleValue)) {
+                        if (is_object($singleValue) && !($singleValue instanceof Phrase)) {
                             $singleValue = $this->buildOutputDataArray($singleValue, $arrayElementType);
                         }
                         $valueResult[] = $this->castValueToType($singleValue, $arrayElementType);