fix: Remove null check for paged Protobuf messages

gapic-generator-java/src/main/java/com/google/api/generator/gapic/composer/common/AbstractServiceStubSettingsClassComposer.java

@@ -65,13 +65,11 @@
 import com.google.api.generator.engine.ast.PrimitiveValue;
 import com.google.api.generator.engine.ast.Reference;
 import com.google.api.generator.engine.ast.ReferenceConstructorExpr;
-import com.google.api.generator.engine.ast.RelationalOperationExpr;
 import com.google.api.generator.engine.ast.ReturnExpr;
 import com.google.api.generator.engine.ast.ScopeNode;
 import com.google.api.generator.engine.ast.Statement;
 import com.google.api.generator.engine.ast.StringObjectValue;
 import com.google.api.generator.engine.ast.SuperObjectValue;
-import com.google.api.generator.engine.ast.TernaryExpr;
 import com.google.api.generator.engine.ast.ThisObjectValue;
 import com.google.api.generator.engine.ast.ThrowExpr;
 import com.google.api.generator.engine.ast.TypeNode;
@@ -788,27 +786,9 @@ private static Expr createPagedListDescriptorAssignExpr(
                 .setGenerics(Arrays.asList(repeatedResponseType.reference()))
                 .build());
 
-    Expr getResponsesExpr;
-    Expr elseExpr;
-    Expr thenExpr;
     if (repeatedResponseType.reference() != null
         && "java.util.Map.Entry".equals(repeatedResponseType.reference().fullName())) {
-      getResponsesExpr =
-          MethodInvocationExpr.builder()
-              .setExprReferenceExpr(payloadVarExpr)
-              .setMethodName(
-                  String.format("get%sMap", JavaStyle.toUpperCamelCase(repeatedFieldName)))
-              .setReturnType(returnType)
-              .build();
-      thenExpr =
-          MethodInvocationExpr.builder()
-              .setStaticReferenceType(
-                  TypeNode.withReference(ConcreteReference.withClazz(Collections.class)))
-              .setGenerics(Arrays.asList(repeatedResponseType.reference()))
-              .setMethodName("emptySet")
-              .setReturnType(returnType)
-              .build();
-      elseExpr =
+      returnExpr =
           MethodInvocationExpr.builder()
               .setMethodName("entrySet")
               .setExprReferenceExpr(
@@ -820,39 +800,14 @@ private static Expr createPagedListDescriptorAssignExpr(
               .setReturnType(returnType)
               .build();
     } else {
-      getResponsesExpr =
+      returnExpr =
           MethodInvocationExpr.builder()
               .setExprReferenceExpr(payloadVarExpr)
               .setMethodName(
                   String.format("get%sList", JavaStyle.toUpperCamelCase(repeatedFieldName)))
               .setReturnType(returnType)
               .build();
-      thenExpr =
-          MethodInvocationExpr.builder()
-              .setStaticReferenceType(
-                  TypeNode.withReference(ConcreteReference.withClazz(ImmutableList.class)))
-              .setGenerics(Arrays.asList(repeatedResponseType.reference()))
-              .setMethodName("of")
-              .setReturnType(returnType)
-              .build();
-      elseExpr = getResponsesExpr;
     }
-    // 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(getResponsesExpr, ValueExpr.createNullExpr());
-
-    returnExpr =
-        TernaryExpr.builder()
-            .setConditionExpr(conditionExpr)
-            .setThenExpr(thenExpr)
-            .setElseExpr(elseExpr)
-            .build();
     anonClassMethods.add(
         methodStarterBuilder
             .setReturnType(returnType)

gapic-generator-java/src/test/java/com/google/api/generator/gapic/composer/grpc/goldens/EchoStubSettings.golden

@@ -180,9 +180,7 @@ public class EchoStubSettings extends StubSettings<EchoStubSettings> {
 
             @Override
             public Iterable<EchoResponse> extractResources(PagedExpandResponse payload) {
-              return payload.getResponsesList() == null
-                  ? ImmutableList.<EchoResponse>of()
-                  : payload.getResponsesList();
+              return payload.getResponsesList();
             }
           };
 
@@ -216,9 +214,7 @@ public class EchoStubSettings extends StubSettings<EchoStubSettings> {
 
             @Override
             public Iterable<EchoResponse> extractResources(PagedExpandResponse payload) {
-              return payload.getResponsesList() == null
-                  ? ImmutableList.<EchoResponse>of()
-                  : payload.getResponsesList();
+              return payload.getResponsesList();
             }
           };
 

gapic-generator-java/src/test/java/com/google/api/generator/gapic/composer/grpc/goldens/LoggingServiceV2StubSettings.golden

@@ -168,9 +168,7 @@ public class LoggingServiceV2StubSettings extends StubSettings<LoggingServiceV2S
 
             @Override
             public Iterable<LogEntry> extractResources(ListLogEntriesResponse payload) {
-              return payload.getEntriesList() == null
-                  ? ImmutableList.<LogEntry>of()
-                  : payload.getEntriesList();
+              return payload.getEntriesList();
             }
           };
 
@@ -217,9 +215,7 @@ public class LoggingServiceV2StubSettings extends StubSettings<LoggingServiceV2S
             @Override
             public Iterable<MonitoredResourceDescriptor> extractResources(
                 ListMonitoredResourceDescriptorsResponse payload) {
-              return payload.getResourceDescriptorsList() == null
-                  ? ImmutableList.<MonitoredResourceDescriptor>of()
-                  : payload.getResourceDescriptorsList();
+              return payload.getResourceDescriptorsList();
             }
           };
 
@@ -253,9 +249,7 @@ public class LoggingServiceV2StubSettings extends StubSettings<LoggingServiceV2S
 
             @Override
             public Iterable<String> extractResources(ListLogsResponse payload) {
-              return payload.getLogNamesList() == null
-                  ? ImmutableList.<String>of()
-                  : payload.getLogNamesList();
+              return payload.getLogNamesList();
             }
           };
 

gapic-generator-java/src/test/java/com/google/api/generator/gapic/composer/grpc/goldens/PublisherStubSettings.golden

@@ -166,9 +166,7 @@ public class PublisherStubSettings extends StubSettings<PublisherStubSettings> {
 
             @Override
             public Iterable<Topic> extractResources(ListTopicsResponse payload) {
-              return payload.getTopicsList() == null
-                  ? ImmutableList.<Topic>of()
-                  : payload.getTopicsList();
+              return payload.getTopicsList();
             }
           };
 
@@ -208,9 +206,7 @@ public class PublisherStubSettings extends StubSettings<PublisherStubSettings> {
 
             @Override
             public Iterable<String> extractResources(ListTopicSubscriptionsResponse payload) {
-              return payload.getSubscriptionsList() == null
-                  ? ImmutableList.<String>of()
-                  : payload.getSubscriptionsList();
+              return payload.getSubscriptionsList();
             }
           };
 
@@ -247,9 +243,7 @@ public class PublisherStubSettings extends StubSettings<PublisherStubSettings> {
 
             @Override
             public Iterable<String> extractResources(ListTopicSnapshotsResponse payload) {
-              return payload.getSnapshotsList() == null
-                  ? ImmutableList.<String>of()
-                  : payload.getSnapshotsList();
+              return payload.getSnapshotsList();
             }
           };
 

gapic-generator-java/src/test/java/com/google/api/generator/gapic/composer/grpcrest/goldens/EchoStubSettings.golden

@@ -186,9 +186,7 @@ public class EchoStubSettings extends StubSettings<EchoStubSettings> {
 
             @Override
             public Iterable<EchoResponse> extractResources(PagedExpandResponse payload) {
-              return payload.getResponsesList() == null
-                  ? ImmutableList.<EchoResponse>of()
-                  : payload.getResponsesList();
+              return payload.getResponsesList();
             }
           };
 
@@ -222,9 +220,7 @@ public class EchoStubSettings extends StubSettings<EchoStubSettings> {
 
             @Override
             public Iterable<EchoResponse> extractResources(PagedExpandResponse payload) {
-              return payload.getResponsesList() == null
-                  ? ImmutableList.<EchoResponse>of()
-                  : payload.getResponsesList();
+              return payload.getResponsesList();
             }
           };
 

showcase/gapic-showcase/src/main/java/com/google/showcase/v1beta1/stub/ComplianceStubSettings.java

@@ -171,9 +171,7 @@ public String extractNextToken(ListLocationsResponse payload) {
 
             @Override
             public Iterable<Location> extractResources(ListLocationsResponse payload) {
-              return payload.getLocationsList() == null
-                  ? ImmutableList.<Location>of()
-                  : payload.getLocationsList();
+              return payload.getLocationsList();
             }
           };
 

showcase/gapic-showcase/src/main/java/com/google/showcase/v1beta1/stub/EchoStubSettings.java

@@ -82,7 +82,6 @@
 import com.google.showcase.v1beta1.WaitRequest;
 import com.google.showcase.v1beta1.WaitResponse;
 import java.io.IOException;
-import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import javax.annotation.Generated;
@@ -225,9 +224,7 @@ public String extractNextToken(PagedExpandResponse payload) {
 
             @Override
             public Iterable<EchoResponse> extractResources(PagedExpandResponse payload) {
-              return payload.getResponsesList() == null
-                  ? ImmutableList.<EchoResponse>of()
-                  : payload.getResponsesList();
+              return payload.getResponsesList();
             }
           };
 
@@ -268,9 +265,7 @@ public String extractNextToken(PagedExpandLegacyMappedResponse payload) {
             @Override
             public Iterable<Map.Entry<String, PagedExpandResponseList>> extractResources(
                 PagedExpandLegacyMappedResponse payload) {
-              return payload.getAlphabetizedMap() == null
-                  ? Collections.<Map.Entry<String, PagedExpandResponseList>>emptySet()
-                  : payload.getAlphabetizedMap().entrySet();
+              return payload.getAlphabetizedMap().entrySet();
             }
           };
 
@@ -304,9 +299,7 @@ public String extractNextToken(ListLocationsResponse payload) {
 
             @Override
             public Iterable<Location> extractResources(ListLocationsResponse payload) {
-              return payload.getLocationsList() == null
-                  ? ImmutableList.<Location>of()
-                  : payload.getLocationsList();
+              return payload.getLocationsList();
             }
           };
 

showcase/gapic-showcase/src/main/java/com/google/showcase/v1beta1/stub/IdentityStubSettings.java

@@ -172,9 +172,7 @@ public String extractNextToken(ListUsersResponse payload) {
 
             @Override
             public Iterable<User> extractResources(ListUsersResponse payload) {
-              return payload.getUsersList() == null
-                  ? ImmutableList.<User>of()
-                  : payload.getUsersList();
+              return payload.getUsersList();
             }
           };
 
@@ -208,9 +206,7 @@ public String extractNextToken(ListLocationsResponse payload) {
 
             @Override
             public Iterable<Location> extractResources(ListLocationsResponse payload) {
-              return payload.getLocationsList() == null
-                  ? ImmutableList.<Location>of()
-                  : payload.getLocationsList();
+              return payload.getLocationsList();
             }
           };
 

showcase/gapic-showcase/src/main/java/com/google/showcase/v1beta1/stub/MessagingStubSettings.java

@@ -233,9 +233,7 @@ public String extractNextToken(ListRoomsResponse payload) {
 
             @Override
             public Iterable<Room> extractResources(ListRoomsResponse payload) {
-              return payload.getRoomsList() == null
-                  ? ImmutableList.<Room>of()
-                  : payload.getRoomsList();
+              return payload.getRoomsList();
             }
           };
 
@@ -269,9 +267,7 @@ public String extractNextToken(ListBlurbsResponse payload) {
 
             @Override
             public Iterable<Blurb> extractResources(ListBlurbsResponse payload) {
-              return payload.getBlurbsList() == null
-                  ? ImmutableList.<Blurb>of()
-                  : payload.getBlurbsList();
+              return payload.getBlurbsList();
             }
           };
 
@@ -305,9 +301,7 @@ public String extractNextToken(ListLocationsResponse payload) {
 
             @Override
             public Iterable<Location> extractResources(ListLocationsResponse payload) {
-              return payload.getLocationsList() == null
-                  ? ImmutableList.<Location>of()
-                  : payload.getLocationsList();
+              return payload.getLocationsList();
             }
           };
 

showcase/gapic-showcase/src/main/java/com/google/showcase/v1beta1/stub/SequenceServiceStubSettings.java

@@ -182,9 +182,7 @@ public String extractNextToken(ListLocationsResponse payload) {
 
             @Override
             public Iterable<Location> extractResources(ListLocationsResponse payload) {
-              return payload.getLocationsList() == null
-                  ? ImmutableList.<Location>of()
-                  : payload.getLocationsList();
+              return payload.getLocationsList();
             }
           };
 

showcase/gapic-showcase/src/main/java/com/google/showcase/v1beta1/stub/TestingStubSettings.java

@@ -185,9 +185,7 @@ public String extractNextToken(ListSessionsResponse payload) {
 
             @Override
             public Iterable<Session> extractResources(ListSessionsResponse payload) {
-              return payload.getSessionsList() == null
-                  ? ImmutableList.<Session>of()
-                  : payload.getSessionsList();
+              return payload.getSessionsList();
             }
           };
 
@@ -221,9 +219,7 @@ public String extractNextToken(ListTestsResponse payload) {
 
             @Override
             public Iterable<Test> extractResources(ListTestsResponse payload) {
-              return payload.getTestsList() == null
-                  ? ImmutableList.<Test>of()
-                  : payload.getTestsList();
+              return payload.getTestsList();
             }
           };
 
@@ -257,9 +253,7 @@ public String extractNextToken(ListLocationsResponse payload) {
 
             @Override
             public Iterable<Location> extractResources(ListLocationsResponse payload) {
-              return payload.getLocationsList() == null
-                  ? ImmutableList.<Location>of()
-                  : payload.getLocationsList();
+              return payload.getLocationsList();
             }
           };
 

showcase/gapic-showcase/src/main/resources/META-INF/native-image/com.google.showcase.v1beta1/reflect-config.json

@@ -332,6 +332,24 @@
     "allDeclaredClasses": true,
     "allPublicClasses": true
   },
+  {
+    "name": "com.google.api.PythonSettings$ExperimentalFeatures",
+    "queryAllDeclaredConstructors": true,
+    "queryAllPublicConstructors": true,
+    "queryAllDeclaredMethods": true,
+    "allPublicMethods": true,
+    "allDeclaredClasses": true,
+    "allPublicClasses": true
+  },
+  {
+    "name": "com.google.api.PythonSettings$ExperimentalFeatures$Builder",
+    "queryAllDeclaredConstructors": true,
+    "queryAllPublicConstructors": true,
+    "queryAllDeclaredMethods": true,
+    "allPublicMethods": true,
+    "allDeclaredClasses": true,
+    "allPublicClasses": true
+  },
   {
     "name": "com.google.api.ResourceDescriptor",
     "queryAllDeclaredConstructors": true,

test/integration/goldens/apigeeconnect/src/com/google/cloud/apigeeconnect/v1/stub/ConnectionServiceStubSettings.java

@@ -150,9 +150,7 @@ public String extractNextToken(ListConnectionsResponse payload) {
 
             @Override
             public Iterable<Connection> extractResources(ListConnectionsResponse payload) {
-              return payload.getConnectionsList() == null
-                  ? ImmutableList.<Connection>of()
-                  : payload.getConnectionsList();
+              return payload.getConnectionsList();
             }
           };