Merge pull request #3190 from aws/zoewang/fixNPEInBatchWriteResult

Fix NPE in BatchWriteResult

Author: zoewangg

services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/model/BatchWriteResult.java

@@ -18,7 +18,9 @@
 import static software.amazon.awssdk.enhanced.dynamodb.internal.EnhancedClientUtils.createKeyFromMap;
 import static software.amazon.awssdk.enhanced.dynamodb.internal.EnhancedClientUtils.readAndTransformSingleItem;
 
+import java.util.ArrayList;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
@@ -56,9 +58,14 @@ public final class BatchWriteResult {
     private final Map<String, List<ItemCollectionMetrics>> itemCollectionMetrics;
 
     private BatchWriteResult(Builder builder) {
-        this.unprocessedRequests = Collections.unmodifiableMap(builder.unprocessedRequests);
-        this.consumedCapacity = Collections.unmodifiableList(builder.consumedCapacity);
-        this.itemCollectionMetrics = builder.itemCollectionMetrics;
+        this.unprocessedRequests = builder.unprocessedRequests == null ?
+                                   Collections.unmodifiableMap(new HashMap<>()) :
+                                   Collections.unmodifiableMap(builder.unprocessedRequests);
+        this.consumedCapacity = builder.consumedCapacity == null ? Collections.unmodifiableList(new ArrayList<>()) :
+                                Collections.unmodifiableList(builder.consumedCapacity);
+        this.itemCollectionMetrics =
+            builder.itemCollectionMetrics == null ? Collections.unmodifiableMap(new HashMap<>()) :
+            Collections.unmodifiableMap(builder.itemCollectionMetrics);
     }
 
     /**

services-custom/dynamodb-enhanced/src/test/java/software/amazon/awssdk/enhanced/dynamodb/model/BatchWriteResultTest.java

@@ -61,9 +61,9 @@ public void setupMappedTables() {
     @Test
     public void builder_minimal() {
         BatchWriteResult builtObject =
-            BatchWriteResult.builder().unprocessedRequests(Collections.EMPTY_MAP).consumedCapacity(ImmutableList.of()).build();
+            BatchWriteResult.builder().unprocessedRequests(Collections.EMPTY_MAP).build();
 
-        Assertions.assertThat(builtObject.itemCollectionMetrics()).isNull();
+        Assertions.assertThat(builtObject.itemCollectionMetrics()).isEmpty();
         Assertions.assertThat(builtObject.consumedCapacity()).isEmpty();
     }