Work around where empty lists are missing from responses (#1621)

Author: GrahamCampbell

src/Result/BatchGetItemOutput.php

@@ -206,7 +206,7 @@ private function populateResultBatchGetResponseMap(array $json): array
     {
         $items = [];
         foreach ($json as $name => $value) {
-            $items[(string) $name] = $this->populateResultItemList($value);
+            $items[(string) $name] = $this->populateResultItemList($value ?? []);
         }
 
         return $items;

src/Result/BatchWriteItemOutput.php

@@ -142,7 +142,7 @@ private function populateResultBatchWriteItemRequestMap(array $json): array
     {
         $items = [];
         foreach ($json as $name => $value) {
-            $items[(string) $name] = $this->populateResultWriteRequests($value);
+            $items[(string) $name] = $this->populateResultWriteRequests($value ?? []);
         }
 
         return $items;
@@ -247,7 +247,7 @@ private function populateResultItemCollectionMetricsPerTable(array $json): array
     {
         $items = [];
         foreach ($json as $name => $value) {
-            $items[(string) $name] = $this->populateResultItemCollectionMetricsMultiple($value);
+            $items[(string) $name] = $this->populateResultItemCollectionMetricsMultiple($value ?? []);
         }
 
         return $items;

src/Result/DescribeEndpointsResponse.php

@@ -29,7 +29,7 @@ protected function populateResult(Response $response): void
     {
         $data = $response->toArray();
 
-        $this->endpoints = $this->populateResultEndpoints($data['Endpoints']);
+        $this->endpoints = $this->populateResultEndpoints($data['Endpoints'] ?? []);
     }
 
     private function populateResultEndpoint(array $json): Endpoint

src/Result/TransactWriteItemsOutput.php

@@ -163,7 +163,7 @@ private function populateResultItemCollectionMetricsPerTable(array $json): array
     {
         $items = [];
         foreach ($json as $name => $value) {
-            $items[(string) $name] = $this->populateResultItemCollectionMetricsMultiple($value);
+            $items[(string) $name] = $this->populateResultItemCollectionMetricsMultiple($value ?? []);
         }
 
         return $items;