chore: Add comment context on null protobuf check [ggj] (#754)

miraleung · web-flow · commit eb1712068f7a · 2021-06-09T14:22:34.000-07:00
* chore: Add comment context on null protobuf check

* Update AbstractServiceStubSettingsClassComposer.java
diff --git a/src/main/java/com/google/api/generator/gapic/composer/common/AbstractServiceStubSettingsClassComposer.java b/src/main/java/com/google/api/generator/gapic/composer/common/AbstractServiceStubSettingsClassComposer.java
@@ -580,6 +580,14 @@ private static Expr createPagedListDescriptorAssignExpr(
                 String.format("get%sList", JavaStyle.toUpperCamelCase(repeatedFieldName)))
             .setReturnType(returnType)
             .build();
+
+    // While protobufs should not be null, this null-check is needed to protect against NPEs
+    // in paged iteration on clients that use legacy HTTP/JSON types, as these clients can
+    // actually return null instead of an empty list.
+    // Context:
+    //   Original issue: https://github.com/googleapis/google-cloud-java/issues/3736
+    //   Relevant discussion where this check was first added:
+    //        https://github.com/googleapis/google-cloud-java/pull/4499#discussion_r257057409
     Expr conditionExpr =
         RelationalOperationExpr.equalToWithExprs(getResponsesListExpr, ValueExpr.createNullExpr());
     Expr thenExpr =
