Java: don't use List<ResourceName> in flattened methods (#2131)

src/main/java/com/google/api/codegen/config/FlatteningConfig.java

@@ -129,4 +129,20 @@ public FlatteningConfig withResourceNamesInSamplesOnly() {
                     Map.Entry::getKey, e -> e.getValue().withResourceNameInSampleOnly()));
     return new AutoValue_FlatteningConfig(newFlattenedFieldConfigs, getFlatteningName());
   }
+
+  public static boolean hasAnyRepeatedResourceNameParameter(FlatteningConfig flatteningGroup) {
+    // Used in Java to prevent generating a flattened method with List<ResourceName> as a parameter
+    // because that has the same type erasure as the version of the flattened method with
+    // List<String> as a parameter.
+
+    // TODO(gapic-generator issue #2137) Only use raw String type for repeated params
+    // not for singular params in the same flattened method.
+    return flatteningGroup
+        .getFlattenedFieldConfigs()
+        .values()
+        .stream()
+        .anyMatch(
+            (FieldConfig fieldConfig) ->
+                fieldConfig.getField().isRepeated() && fieldConfig.useResourceNameType());
+  }
 }

src/main/java/com/google/api/codegen/discogapic/transformer/java/JavaDiscoGapicRequestToViewTransformer.java

@@ -158,6 +158,9 @@ private RequestObjectParamView getRequestObjectParams(
       for (FlatteningConfig flatteningGroup : methodConfig.getFlatteningConfigs()) {
         MethodContext flattenedMethodContext =
             context.asFlattenedMethodContext(method, flatteningGroup);
+        if (FlatteningConfig.hasAnyRepeatedResourceNameParameter(flatteningGroup)) {
+          flattenedMethodContext = flattenedMethodContext.withResourceNamesInSamplesOnly();
+        }
         Iterable<FieldConfig> fieldConfigs =
             flattenedMethodContext.getFlatteningConfig().getFlattenedFieldConfigs().values();
         for (FieldConfig fieldConfig : fieldConfigs) {

src/main/java/com/google/api/codegen/transformer/java/JavaMethodViewGenerator.java

@@ -62,8 +62,10 @@ public List<StaticLangApiMethodView> generateApiMethods(InterfaceContext context
           for (FlatteningConfig flatteningGroup : methodConfig.getFlatteningConfigs()) {
             MethodContext flattenedMethodContext =
                 context.asFlattenedMethodContext(method, flatteningGroup);
-            apiMethods.add(
-                clientMethodTransformer.generatePagedFlattenedMethod(flattenedMethodContext));
+            if (!FlatteningConfig.hasAnyRepeatedResourceNameParameter(flatteningGroup)) {
+              apiMethods.add(
+                  clientMethodTransformer.generatePagedFlattenedMethod(flattenedMethodContext));
+            }
             if (hasAnyResourceNameParameter(flatteningGroup)) {
               apiMethods.add(
                   clientMethodTransformer.generatePagedFlattenedMethod(
@@ -105,6 +107,9 @@ public List<StaticLangApiMethodView> generateApiMethods(InterfaceContext context
           for (FlatteningConfig flatteningGroup : methodConfig.getFlatteningConfigs()) {
             MethodContext flattenedMethodContext =
                 context.asFlattenedMethodContext(method, flatteningGroup);
+            if (FlatteningConfig.hasAnyRepeatedResourceNameParameter(flatteningGroup)) {
+              flattenedMethodContext = flattenedMethodContext.withResourceNamesInSamplesOnly();
+            }
             apiMethods.add(
                 clientMethodTransformer.generateAsyncOperationFlattenedMethod(
                     flattenedMethodContext));
@@ -126,6 +131,9 @@ public List<StaticLangApiMethodView> generateApiMethods(InterfaceContext context
           for (FlatteningConfig flatteningGroup : methodConfig.getFlatteningConfigs()) {
             MethodContext flattenedMethodContext =
                 context.asFlattenedMethodContext(method, flatteningGroup);
+            if (FlatteningConfig.hasAnyRepeatedResourceNameParameter(flatteningGroup)) {
+              flattenedMethodContext = flattenedMethodContext.withResourceNamesInSamplesOnly();
+            }
             apiMethods.add(clientMethodTransformer.generateFlattenedMethod(flattenedMethodContext));
 
             if (hasAnyResourceNameParameter(flatteningGroup)) {

src/main/java/com/google/api/codegen/transformer/java/JavaSurfaceTestTransformer.java

@@ -174,6 +174,9 @@ SmokeTestClassView.Builder createSmokeTestClassViewBuilder(InterfaceContext cont
         testCaseTransformer.getSmokeTestFlatteningGroup(
             context.getMethodConfig(method), context.getInterfaceConfig().getSmokeTestConfig());
     MethodContext methodContext = context.asFlattenedMethodContext(method, flatteningGroup);
+    if (FlatteningConfig.hasAnyRepeatedResourceNameParameter(flatteningGroup)) {
+      methodContext = methodContext.withResourceNamesInSamplesOnly();
+    }
 
     SmokeTestClassView.Builder testClass = SmokeTestClassView.newBuilder();
     StaticLangApiMethodView apiMethodView = createSmokeTestCaseApiMethodView(methodContext);
@@ -304,6 +307,10 @@ private List<TestCaseView> createTestCaseViews(InterfaceContext context) {
         }
         for (FlatteningConfig flatteningGroup : methodConfig.getFlatteningConfigs()) {
           MethodContext methodContext = context.asFlattenedMethodContext(method, flatteningGroup);
+          if (FlatteningConfig.hasAnyRepeatedResourceNameParameter(flatteningGroup)) {
+            methodContext = methodContext.withResourceNamesInSamplesOnly();
+            flatteningGroup = methodContext.getFlatteningConfig();
+          }
           InitCodeContext initCodeContext =
               initCodeTransformer.createRequestInitCodeContext(
                   methodContext,