MAGETWO-70020: Improved type hints and declarations for \Magento\Quote\Model\Quote\Address\Total #9986

 - Merge Pull Request #9986 from schmengler/magento2:quote-total-type
 - Merged commits:
   1. fb3b977
   2. 160327b
   3. f7aea83
   4. 99a4d69

Author: Oleksii Korshenko

app/code/Magento/Quote/Model/Quote.php

@@ -1944,7 +1944,7 @@ public function collectTotals()
     /**
      * Get all quote totals (sorted by priority)
      *
-     * @return array
+     * @return Address\Total[]
      */
     public function getTotals()
     {

app/code/Magento/Quote/Model/Quote/Address/Total.php

@@ -6,19 +6,21 @@
 namespace Magento\Quote\Model\Quote\Address;
 
 /**
+ * @method string getCode()
+ *
  * @api
  */
 class Total extends \Magento\Framework\DataObject
 {
     /**
      * @var array
      */
-    protected $totalAmounts;
+    protected $totalAmounts = [];
 
     /**
      * @var array
      */
-    protected $baseTotalAmounts;
+    protected $baseTotalAmounts = [];
 
     /**
      * Serializer interface instance.

app/code/Magento/Quote/Model/Quote/Address/TotalFactory.php

@@ -33,9 +33,9 @@ public function __construct(\Magento\Framework\ObjectManagerInterface $objManage
      *
      * @param string $instanceName
      * @param array $data
-     * @return \Magento\Quote\Model\Quote\Address\Total\AbstractTotal
+     * @return Total\AbstractTotal|Total
      */
-    public function create($instanceName, array $data = [])
+    public function create($instanceName = Total::class, array $data = [])
     {
         return $this->_objectManager->create($instanceName, $data);
     }

app/code/Magento/Quote/Model/Quote/TotalsReader.php

@@ -35,12 +35,12 @@ public function __construct(
     /**
      * @param \Magento\Quote\Model\Quote $quote
      * @param array $total
-     * @return array
+     * @return Total[]
      */
     public function fetch(\Magento\Quote\Model\Quote $quote, array $total)
     {
         $output = [];
-        $total = $this->totalFactory->create(\Magento\Quote\Model\Quote\Address\Total::class)->setData($total);
+        $total = $this->totalFactory->create()->setData($total);
         /** @var ReaderInterface $reader */
         foreach ($this->collectorList->getCollectors($quote->getStoreId()) as $reader) {
             $data = $reader->fetch($quote, $total);
@@ -62,7 +62,7 @@ public function fetch(\Magento\Quote\Model\Quote $quote, array $total)
 
     /**
      * @param array $total
-     * @return Total|array
+     * @return Total|Total[]
      */
     protected function convert($total)
     {
@@ -73,22 +73,20 @@ protected function convert($total)
         if (count(array_column($total, 'code')) > 0) {
             $totals = [];
             foreach ($total as $item) {
-                $totals[] = $this->totalFactory->create(
-                    \Magento\Quote\Model\Quote\Address\Total::class
-                )->setData($item);
+                $totals[] = $this->totalFactory->create()->setData($item);
             }
             return $totals;
         }
 
-        return $this->totalFactory->create(\Magento\Quote\Model\Quote\Address\Total::class)->setData($total);
+        return $this->totalFactory->create()->setData($total);
     }
 
     /**
      * @param Total $totalInstance
-     * @param array $output
-     * @return array
+     * @param Total[] $output
+     * @return Total[]
      */
-    protected function merge($totalInstance, $output)
+    protected function merge(Total $totalInstance, $output)
     {
         if (array_key_exists($totalInstance->getCode(), $output)) {
             $output[$totalInstance->getCode()] = $output[$totalInstance->getCode()]->addData(