diff --git a/app/code/Magento/Catalog/Api/Data/CategoryAttributeSearchResultsInterface.php b/app/code/Magento/Catalog/Api/Data/CategoryAttributeSearchResultsInterface.php
index 9decc3aaab231..396e779c7a22e 100644
--- a/app/code/Magento/Catalog/Api/Data/CategoryAttributeSearchResultsInterface.php
+++ b/app/code/Magento/Catalog/Api/Data/CategoryAttributeSearchResultsInterface.php
@@ -24,5 +24,5 @@ public function getItems();
      * @param \Magento\Catalog\Api\Data\CategoryAttributeInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Catalog/Api/Data/ProductAttributeSearchResultsInterface.php b/app/code/Magento/Catalog/Api/Data/ProductAttributeSearchResultsInterface.php
index 1d8ed8d78c7ac..efb35c89a3751 100644
--- a/app/code/Magento/Catalog/Api/Data/ProductAttributeSearchResultsInterface.php
+++ b/app/code/Magento/Catalog/Api/Data/ProductAttributeSearchResultsInterface.php
@@ -24,5 +24,5 @@ public function getItems();
      * @param \Magento\Catalog\Api\Data\ProductAttributeInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Catalog/Api/Data/ProductSearchResultsInterface.php b/app/code/Magento/Catalog/Api/Data/ProductSearchResultsInterface.php
index 67c3b5ddef820..888a795f73a5b 100644
--- a/app/code/Magento/Catalog/Api/Data/ProductSearchResultsInterface.php
+++ b/app/code/Magento/Catalog/Api/Data/ProductSearchResultsInterface.php
@@ -24,5 +24,5 @@ public function getItems();
      * @param \Magento\Catalog\Api\Data\ProductInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/CatalogInventory/Api/Data/StockCollectionInterface.php b/app/code/Magento/CatalogInventory/Api/Data/StockCollectionInterface.php
index c3f4b5dcc4d01..a656b049c93a8 100644
--- a/app/code/Magento/CatalogInventory/Api/Data/StockCollectionInterface.php
+++ b/app/code/Magento/CatalogInventory/Api/Data/StockCollectionInterface.php
@@ -30,5 +30,5 @@ public function getItems();
      * @param \Magento\CatalogInventory\Api\Data\StockInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/CatalogInventory/Api/Data/StockItemCollectionInterface.php b/app/code/Magento/CatalogInventory/Api/Data/StockItemCollectionInterface.php
index bd649dc6f41c3..ee670c352f18a 100644
--- a/app/code/Magento/CatalogInventory/Api/Data/StockItemCollectionInterface.php
+++ b/app/code/Magento/CatalogInventory/Api/Data/StockItemCollectionInterface.php
@@ -30,7 +30,7 @@ public function getItems();
      * @param \Magento\CatalogInventory\Api\Data\StockItemInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 
     /**
      * Get search criteria.
diff --git a/app/code/Magento/CatalogInventory/Api/Data/StockStatusCollectionInterface.php b/app/code/Magento/CatalogInventory/Api/Data/StockStatusCollectionInterface.php
index 6f53ba8238eb0..a06aa1ebd0a4a 100644
--- a/app/code/Magento/CatalogInventory/Api/Data/StockStatusCollectionInterface.php
+++ b/app/code/Magento/CatalogInventory/Api/Data/StockStatusCollectionInterface.php
@@ -27,7 +27,7 @@ public function getItems();
      * @param \Magento\CatalogInventory\Api\Data\StockStatusInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 
     /**
      * Get search criteria.
diff --git a/app/code/Magento/Cms/Api/Data/BlockSearchResultsInterface.php b/app/code/Magento/Cms/Api/Data/BlockSearchResultsInterface.php
index 682910c4cdcab..7e3335d206a18 100644
--- a/app/code/Magento/Cms/Api/Data/BlockSearchResultsInterface.php
+++ b/app/code/Magento/Cms/Api/Data/BlockSearchResultsInterface.php
@@ -26,5 +26,5 @@ public function getItems();
      * @param \Magento\Cms\Api\Data\BlockInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Cms/Api/Data/PageSearchResultsInterface.php b/app/code/Magento/Cms/Api/Data/PageSearchResultsInterface.php
index 58141ae9bf5df..155a0961cf7bf 100644
--- a/app/code/Magento/Cms/Api/Data/PageSearchResultsInterface.php
+++ b/app/code/Magento/Cms/Api/Data/PageSearchResultsInterface.php
@@ -26,5 +26,5 @@ public function getItems();
      * @param \Magento\Cms\Api\Data\PageInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Customer/Api/Data/AddressSearchResultsInterface.php b/app/code/Magento/Customer/Api/Data/AddressSearchResultsInterface.php
index f74c607091c2c..bc3cc9c56caef 100644
--- a/app/code/Magento/Customer/Api/Data/AddressSearchResultsInterface.php
+++ b/app/code/Magento/Customer/Api/Data/AddressSearchResultsInterface.php
@@ -26,5 +26,5 @@ public function getItems();
      * @param \Magento\Customer\Api\Data\AddressInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Customer/Api/Data/CustomerSearchResultsInterface.php b/app/code/Magento/Customer/Api/Data/CustomerSearchResultsInterface.php
index 9cf801526d308..db5aec8ef40ef 100644
--- a/app/code/Magento/Customer/Api/Data/CustomerSearchResultsInterface.php
+++ b/app/code/Magento/Customer/Api/Data/CustomerSearchResultsInterface.php
@@ -26,5 +26,5 @@ public function getItems();
      * @param \Magento\Customer\Api\Data\CustomerInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Customer/Api/Data/GroupSearchResultsInterface.php b/app/code/Magento/Customer/Api/Data/GroupSearchResultsInterface.php
index f8effeeb8fc5a..818baf4a3c26d 100644
--- a/app/code/Magento/Customer/Api/Data/GroupSearchResultsInterface.php
+++ b/app/code/Magento/Customer/Api/Data/GroupSearchResultsInterface.php
@@ -26,5 +26,5 @@ public function getItems();
      * @param \Magento\Customer\Api\Data\GroupInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Eav/Api/Data/AttributeGroupSearchResultsInterface.php b/app/code/Magento/Eav/Api/Data/AttributeGroupSearchResultsInterface.php
index fd9a4416c42ca..6c7a6349ddfcc 100644
--- a/app/code/Magento/Eav/Api/Data/AttributeGroupSearchResultsInterface.php
+++ b/app/code/Magento/Eav/Api/Data/AttributeGroupSearchResultsInterface.php
@@ -21,5 +21,5 @@ public function getItems();
      * @param \Magento\Eav\Api\Data\AttributeGroupInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Eav/Api/Data/AttributeSearchResultsInterface.php b/app/code/Magento/Eav/Api/Data/AttributeSearchResultsInterface.php
index ccf026345d871..1b010cae41f30 100644
--- a/app/code/Magento/Eav/Api/Data/AttributeSearchResultsInterface.php
+++ b/app/code/Magento/Eav/Api/Data/AttributeSearchResultsInterface.php
@@ -21,5 +21,5 @@ public function getItems();
      * @param \Magento\Eav\Api\Data\AttributeInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Eav/Api/Data/AttributeSetSearchResultsInterface.php b/app/code/Magento/Eav/Api/Data/AttributeSetSearchResultsInterface.php
index ef0d07da39cd2..4840175ebd194 100644
--- a/app/code/Magento/Eav/Api/Data/AttributeSetSearchResultsInterface.php
+++ b/app/code/Magento/Eav/Api/Data/AttributeSetSearchResultsInterface.php
@@ -21,5 +21,5 @@ public function getItems();
      * @param \Magento\Eav\Api\Data\AttributeSetInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Quote/Api/Data/CartSearchResultsInterface.php b/app/code/Magento/Quote/Api/Data/CartSearchResultsInterface.php
index 8a161def692b0..9a4bbbfee3b19 100644
--- a/app/code/Magento/Quote/Api/Data/CartSearchResultsInterface.php
+++ b/app/code/Magento/Quote/Api/Data/CartSearchResultsInterface.php
@@ -35,7 +35,7 @@ public function getItems();
      * @param \Magento\Quote\Api\Data\CartInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 
     /**
      * Get search criteria.
@@ -50,7 +50,7 @@ public function getSearchCriteria();
      * @param \Magento\Framework\Api\SearchCriteriaInterface $searchCriteria
      * @return $this
      */
-    public function setSearchCriteria(\Magento\Framework\Api\SearchCriteriaInterface $searchCriteria = null);
+    public function setSearchCriteria(\Magento\Framework\Api\SearchCriteriaInterface $searchCriteria);
 
     /**
      * Get total count.
diff --git a/app/code/Magento/Sales/Api/Data/CreditmemoCommentSearchResultInterface.php b/app/code/Magento/Sales/Api/Data/CreditmemoCommentSearchResultInterface.php
index 6c669297ee40b..a99bc34c29820 100644
--- a/app/code/Magento/Sales/Api/Data/CreditmemoCommentSearchResultInterface.php
+++ b/app/code/Magento/Sales/Api/Data/CreditmemoCommentSearchResultInterface.php
@@ -29,5 +29,5 @@ public function getItems();
      * @param \Magento\Sales\Api\Data\CreditmemoCommentInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Sales/Api/Data/CreditmemoItemSearchResultInterface.php b/app/code/Magento/Sales/Api/Data/CreditmemoItemSearchResultInterface.php
index ad037370d3485..329c36ba27869 100644
--- a/app/code/Magento/Sales/Api/Data/CreditmemoItemSearchResultInterface.php
+++ b/app/code/Magento/Sales/Api/Data/CreditmemoItemSearchResultInterface.php
@@ -29,5 +29,5 @@ public function getItems();
      * @param \Magento\Sales\Api\Data\CreditmemoItemInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Sales/Api/Data/CreditmemoSearchResultInterface.php b/app/code/Magento/Sales/Api/Data/CreditmemoSearchResultInterface.php
index 854443a60eca6..38fa62e51bd11 100644
--- a/app/code/Magento/Sales/Api/Data/CreditmemoSearchResultInterface.php
+++ b/app/code/Magento/Sales/Api/Data/CreditmemoSearchResultInterface.php
@@ -28,5 +28,5 @@ public function getItems();
      * @param \Magento\Sales\Api\Data\CreditmemoInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Sales/Api/Data/InvoiceCommentSearchResultInterface.php b/app/code/Magento/Sales/Api/Data/InvoiceCommentSearchResultInterface.php
index fd46600844985..3d18d051536d1 100644
--- a/app/code/Magento/Sales/Api/Data/InvoiceCommentSearchResultInterface.php
+++ b/app/code/Magento/Sales/Api/Data/InvoiceCommentSearchResultInterface.php
@@ -27,5 +27,5 @@ public function getItems();
      * @param \Magento\Sales\Api\Data\InvoiceCommentInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Sales/Api/Data/InvoiceItemSearchResultInterface.php b/app/code/Magento/Sales/Api/Data/InvoiceItemSearchResultInterface.php
index 50132c276f220..519ff0f1e6fed 100644
--- a/app/code/Magento/Sales/Api/Data/InvoiceItemSearchResultInterface.php
+++ b/app/code/Magento/Sales/Api/Data/InvoiceItemSearchResultInterface.php
@@ -26,5 +26,5 @@ public function getItems();
      * @param \Magento\Sales\Api\Data\InvoiceItemInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Sales/Api/Data/InvoiceSearchResultInterface.php b/app/code/Magento/Sales/Api/Data/InvoiceSearchResultInterface.php
index 3be17c7084718..a0cc54740867e 100644
--- a/app/code/Magento/Sales/Api/Data/InvoiceSearchResultInterface.php
+++ b/app/code/Magento/Sales/Api/Data/InvoiceSearchResultInterface.php
@@ -26,5 +26,5 @@ public function getItems();
      * @param \Magento\Sales\Api\Data\InvoiceInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Sales/Api/Data/OrderAddressSearchResultInterface.php b/app/code/Magento/Sales/Api/Data/OrderAddressSearchResultInterface.php
index d0a9d55c08c6a..6b6964f847557 100644
--- a/app/code/Magento/Sales/Api/Data/OrderAddressSearchResultInterface.php
+++ b/app/code/Magento/Sales/Api/Data/OrderAddressSearchResultInterface.php
@@ -28,5 +28,5 @@ public function getItems();
      * @param \Magento\Sales\Api\Data\OrderAddressInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Sales/Api/Data/OrderItemSearchResultInterface.php b/app/code/Magento/Sales/Api/Data/OrderItemSearchResultInterface.php
index 4fa7587d80fab..20a9ee79f44a5 100644
--- a/app/code/Magento/Sales/Api/Data/OrderItemSearchResultInterface.php
+++ b/app/code/Magento/Sales/Api/Data/OrderItemSearchResultInterface.php
@@ -28,5 +28,5 @@ public function getItems();
      * @param \Magento\Sales\Api\Data\OrderItemInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Sales/Api/Data/OrderPaymentSearchResultInterface.php b/app/code/Magento/Sales/Api/Data/OrderPaymentSearchResultInterface.php
index 474b015aff872..3f19b2d9d4a66 100644
--- a/app/code/Magento/Sales/Api/Data/OrderPaymentSearchResultInterface.php
+++ b/app/code/Magento/Sales/Api/Data/OrderPaymentSearchResultInterface.php
@@ -28,5 +28,5 @@ public function getItems();
      * @param \Magento\Sales\Api\Data\OrderPaymentInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Sales/Api/Data/OrderStatusHistorySearchResultInterface.php b/app/code/Magento/Sales/Api/Data/OrderStatusHistorySearchResultInterface.php
index 05d2ffc7e90fb..3ff98f4153130 100644
--- a/app/code/Magento/Sales/Api/Data/OrderStatusHistorySearchResultInterface.php
+++ b/app/code/Magento/Sales/Api/Data/OrderStatusHistorySearchResultInterface.php
@@ -28,5 +28,5 @@ public function getItems();
      * @param \Magento\Sales\Api\Data\OrderStatusHistoryInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Sales/Api/Data/ShipmentCommentSearchResultInterface.php b/app/code/Magento/Sales/Api/Data/ShipmentCommentSearchResultInterface.php
index 442f6ee17c215..4a3847d906879 100644
--- a/app/code/Magento/Sales/Api/Data/ShipmentCommentSearchResultInterface.php
+++ b/app/code/Magento/Sales/Api/Data/ShipmentCommentSearchResultInterface.php
@@ -27,5 +27,5 @@ public function getItems();
      * @param \Magento\Sales\Api\Data\ShipmentCommentInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Sales/Api/Data/ShipmentItemSearchResultInterface.php b/app/code/Magento/Sales/Api/Data/ShipmentItemSearchResultInterface.php
index 54b6f999fba13..ffa2e5417b57a 100644
--- a/app/code/Magento/Sales/Api/Data/ShipmentItemSearchResultInterface.php
+++ b/app/code/Magento/Sales/Api/Data/ShipmentItemSearchResultInterface.php
@@ -27,5 +27,5 @@ public function getItems();
      * @param \Magento\Sales\Api\Data\ShipmentItemInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Sales/Api/Data/ShipmentSearchResultInterface.php b/app/code/Magento/Sales/Api/Data/ShipmentSearchResultInterface.php
index 41aed7955a1bf..6a3e77477faa8 100644
--- a/app/code/Magento/Sales/Api/Data/ShipmentSearchResultInterface.php
+++ b/app/code/Magento/Sales/Api/Data/ShipmentSearchResultInterface.php
@@ -29,5 +29,5 @@ public function getItems();
      * @param \Magento\Sales\Api\Data\ShipmentInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Sales/Api/Data/ShipmentTrackSearchResultInterface.php b/app/code/Magento/Sales/Api/Data/ShipmentTrackSearchResultInterface.php
index e34a4003452d6..d6e20cf1ae9e1 100644
--- a/app/code/Magento/Sales/Api/Data/ShipmentTrackSearchResultInterface.php
+++ b/app/code/Magento/Sales/Api/Data/ShipmentTrackSearchResultInterface.php
@@ -28,5 +28,5 @@ public function getItems();
      * @param \Magento\Sales\Api\Data\ShipmentTrackInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Sales/Api/Data/TransactionSearchResultInterface.php b/app/code/Magento/Sales/Api/Data/TransactionSearchResultInterface.php
index 20e23a5f9bd33..3f783f9f811ea 100644
--- a/app/code/Magento/Sales/Api/Data/TransactionSearchResultInterface.php
+++ b/app/code/Magento/Sales/Api/Data/TransactionSearchResultInterface.php
@@ -26,5 +26,5 @@ public function getItems();
      * @param \Magento\Sales\Api\Data\TransactionInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Tax/Api/Data/TaxClassSearchResultsInterface.php b/app/code/Magento/Tax/Api/Data/TaxClassSearchResultsInterface.php
index 0124ff349f686..828f05088c191 100644
--- a/app/code/Magento/Tax/Api/Data/TaxClassSearchResultsInterface.php
+++ b/app/code/Magento/Tax/Api/Data/TaxClassSearchResultsInterface.php
@@ -25,5 +25,5 @@ public function getItems();
      * @param \Magento\Tax\Api\Data\TaxClassInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Tax/Api/Data/TaxRateSearchResultsInterface.php b/app/code/Magento/Tax/Api/Data/TaxRateSearchResultsInterface.php
index b467b844d19a3..cf037ad071bd3 100644
--- a/app/code/Magento/Tax/Api/Data/TaxRateSearchResultsInterface.php
+++ b/app/code/Magento/Tax/Api/Data/TaxRateSearchResultsInterface.php
@@ -28,5 +28,5 @@ public function getItems();
      * @param \Magento\Tax\Api\Data\TaxRateInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Tax/Api/Data/TaxRuleSearchResultsInterface.php b/app/code/Magento/Tax/Api/Data/TaxRuleSearchResultsInterface.php
index dc0e83dcfe724..1d141188169d8 100644
--- a/app/code/Magento/Tax/Api/Data/TaxRuleSearchResultsInterface.php
+++ b/app/code/Magento/Tax/Api/Data/TaxRuleSearchResultsInterface.php
@@ -25,5 +25,5 @@ public function getItems();
      * @param \Magento\Tax\Api\Data\TaxRuleInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/app/code/Magento/Tax/Test/Unit/Model/TaxClass/RepositoryTest.php b/app/code/Magento/Tax/Test/Unit/Model/TaxClass/RepositoryTest.php
index bfab6b77acc7f..277c10f7b2bfc 100644
--- a/app/code/Magento/Tax/Test/Unit/Model/TaxClass/RepositoryTest.php
+++ b/app/code/Magento/Tax/Test/Unit/Model/TaxClass/RepositoryTest.php
@@ -222,6 +222,7 @@ public function testGetList()
 
         $collection->expects($this->any())->method('getSize')->willReturn(2);
         $collection->expects($this->any())->method('setItems')->with([$taxClassOne, $taxClassTwo]);
+        $collection->expects($this->any())->method('getItems')->willReturn([$taxClassOne, $taxClassTwo]);
         $collection->expects($this->once())->method('setCurPage')->with(0);
         $collection->expects($this->once())->method('setPageSize')->with(20);
 
diff --git a/app/code/Magento/Ui/Api/Data/BookmarkSearchResultsInterface.php b/app/code/Magento/Ui/Api/Data/BookmarkSearchResultsInterface.php
index ba120e37f1e4f..36df199ab9b56 100644
--- a/app/code/Magento/Ui/Api/Data/BookmarkSearchResultsInterface.php
+++ b/app/code/Magento/Ui/Api/Data/BookmarkSearchResultsInterface.php
@@ -26,5 +26,5 @@ public function getItems();
      * @param \Magento\Ui\Api\Data\BookmarkInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 }
diff --git a/lib/internal/Magento/Framework/Api/SearchResults.php b/lib/internal/Magento/Framework/Api/SearchResults.php
index e828617e416da..2a2ebba53e28f 100644
--- a/lib/internal/Magento/Framework/Api/SearchResults.php
+++ b/lib/internal/Magento/Framework/Api/SearchResults.php
@@ -9,7 +9,7 @@
 /**
  * SearchResults Service Data Object used for the search service requests
  */
-class SearchResults extends AbstractSimpleObject
+class SearchResults extends AbstractSimpleObject implements SearchResultsInterface
 {
     const KEY_ITEMS = 'items';
     const KEY_SEARCH_CRITERIA = 'search_criteria';
@@ -49,10 +49,10 @@ public function getSearchCriteria()
     /**
      * Set search criteria
      *
-     * @param \Magento\Framework\Api\SearchCriteria $searchCriteria
+     * @param SearchCriteriaInterface $searchCriteria
      * @return $this
      */
-    public function setSearchCriteria(\Magento\Framework\Api\SearchCriteria $searchCriteria)
+    public function setSearchCriteria(\Magento\Framework\Api\SearchCriteriaInterface $searchCriteria)
     {
         return $this->setData(self::KEY_SEARCH_CRITERIA, $searchCriteria);
     }
diff --git a/lib/internal/Magento/Framework/Api/SearchResultsInterface.php b/lib/internal/Magento/Framework/Api/SearchResultsInterface.php
index 08c86090cbfcf..67870b2870139 100644
--- a/lib/internal/Magento/Framework/Api/SearchResultsInterface.php
+++ b/lib/internal/Magento/Framework/Api/SearchResultsInterface.php
@@ -26,7 +26,7 @@ public function getItems();
      * @param \Magento\Framework\Api\ExtensibleDataInterface[] $items
      * @return $this
      */
-    public function setItems(array $items = null);
+    public function setItems(array $items);
 
     /**
      * Get search criteria.
@@ -41,7 +41,7 @@ public function getSearchCriteria();
      * @param \Magento\Framework\Api\SearchCriteriaInterface $searchCriteria
      * @return $this
      */
-    public function setSearchCriteria(\Magento\Framework\Api\SearchCriteriaInterface $searchCriteria = null);
+    public function setSearchCriteria(\Magento\Framework\Api\SearchCriteriaInterface $searchCriteria);
 
     /**
      * Get total count.