MAGETWO-53366: Tax Report does not display any records

- modifying logic for converter empty arrays
- fix indentation for a constant

Author: cpartica

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

@@ -73,8 +73,8 @@ public function afterConvert(QuoteAddressToOrder $subject, OrderInterface $order
                         $itemAppliedTaxesModified[$key]['associated_item_id'] = $itemAppliedTax['associated_item_id'];
                         $itemAppliedTaxesModified[$key]['applied_taxes'][] = $itemAppliedTax;
                     }
-                } elseif (!empty($itemAppliedTaxItem)) {
-                    $itemAppliedTaxesModified[$key] = $itemAppliedTaxItem;
+                } elseif (is_array($itemAppliedTaxItem) && empty($itemAppliedTaxItem)) {
+                    $itemAppliedTaxesModified[$key] = [];
                 }
             }
             $extensionAttributes->setItemAppliedTaxes($itemAppliedTaxesModified);

app/code/Magento/Tax/Model/Sales/Order/Tax.php

@@ -31,7 +31,7 @@ class Tax extends \Magento\Framework\Model\AbstractExtensibleModel implements
     const KEY_PERCENT     = 'percent';
     const KEY_AMOUNT      = 'amount';
     const KEY_BASE_AMOUNT = 'base_amount';
-    const KEY_RATES = 'rates';
+    const KEY_RATES       = 'rates';
     /**#@-*/
 
     /**