wrapped result with immutable list

Author: roamariei

services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/internal/TableIndices.java

@@ -15,6 +15,7 @@
 
 package software.amazon.awssdk.enhanced.dynamodb.internal;
 
+import java.util.Collections;
 import java.util.List;
 import java.util.stream.Collectors;
 import software.amazon.awssdk.annotations.SdkInternalApi;
@@ -33,19 +34,19 @@ public TableIndices(List<IndexMetadata> indices) {
     }
 
     public List<EnhancedLocalSecondaryIndex> localSecondaryIndices() {
-        return indices.stream()
-                      .filter(index -> !TableMetadata.primaryIndexName().equals(index.name()))
-                      .filter(index -> !index.partitionKey().isPresent())
-                      .map(TableIndices::mapIndexMetadataToEnhancedLocalSecondaryIndex)
-                      .collect(Collectors.toList());
+        return Collections.unmodifiableList(indices.stream()
+                                                   .filter(index -> !TableMetadata.primaryIndexName().equals(index.name()))
+                                                   .filter(index -> !index.partitionKey().isPresent())
+                                                   .map(TableIndices::mapIndexMetadataToEnhancedLocalSecondaryIndex)
+                                                   .collect(Collectors.toList()));
     }
 
     public List<EnhancedGlobalSecondaryIndex> globalSecondaryIndices() {
-        return indices.stream()
-                      .filter(index -> !TableMetadata.primaryIndexName().equals(index.name()))
-                      .filter(index -> index.partitionKey().isPresent())
-                      .map(TableIndices::mapIndexMetadataToEnhancedGlobalSecondaryIndex)
-                      .collect(Collectors.toList());
+        return Collections.unmodifiableList(indices.stream()
+                                                   .filter(index -> !TableMetadata.primaryIndexName().equals(index.name()))
+                                                   .filter(index -> index.partitionKey().isPresent())
+                                                   .map(TableIndices::mapIndexMetadataToEnhancedGlobalSecondaryIndex)
+                                                   .collect(Collectors.toList()));
     }
 
     private static EnhancedLocalSecondaryIndex mapIndexMetadataToEnhancedLocalSecondaryIndex(IndexMetadata indexMetadata) {