fix(mixins): enable RPC overrides to clobber mixed-in RPCs

src/main/java/com/google/api/generator/gapic/composer/GrpcServiceStubClassComposer.java

@@ -105,7 +105,7 @@ public class GrpcServiceStubClassComposer implements ClassComposer {
   // Legacy support for the original reroute_to_grpc_interface option in gapic.yaml. These two APIs
   // predate the modern way, which is to add the RPCs directly into the proto.
   private static final Set<String> REROUTE_TO_GRPC_INTERFACE_SERVICE_ALLOWLIST =
-      new HashSet<>(Arrays.asList("google.cloud.kms.v1", "google.pubsub.v1"));
+      new HashSet<>(Arrays.asList("google.pubsub.v1"));
   private static final Set<String> REROUTE_TO_GRPC_INTERFACE_IAM_METHOD_ALLOWLIST =
       new HashSet<>(Arrays.asList("SetIamPolicy", "GetIamPolicy", "TestIamPermissions"));
 

src/main/java/com/google/api/generator/gapic/protoparser/Parser.java

@@ -229,6 +229,14 @@ public static List<Service> parseServices(
                 .filter(a -> MIXIN_ALLOWLIST.contains(a.getName()))
                 .map(a -> a.getName())
                 .collect(Collectors.toSet());
+    Set<String> apiDefinedRpcs = new HashSet<>();
+    for (Service service : services) {
+      if (blockedCodegenMixinApis.contains(service)) {
+        continue;
+      }
+      apiDefinedRpcs.addAll(
+          service.methods().stream().map(m -> m.name()).collect(Collectors.toSet()));
+    }
     // Mix-in APIs only if the protos are present and they're defined in the service.yaml file.
     Set<Service> outputMixinServiceSet = new HashSet<>();
     if (servicesContainBlocklistedApi && !mixedInApis.isEmpty()) {
@@ -241,13 +249,18 @@ public static List<Service> parseServices(
               String.format("%s.%s", mixinService.protoPakkage(), mixinService.name()))) {
             continue;
           }
-          List<Method> mixinMethods = new ArrayList<>(mixinService.methods());
-          mixinMethods.forEach(
-              m ->
-                  updatedMethods.add(
-                      m.toBuilder()
-                          .setMixedInApiName(serviceFullNameFn.apply(mixinService))
-                          .build()));
+          mixinService
+              .methods()
+              .forEach(
+                  m -> {
+                    // Overridden RPCs defined in the protos take precedence.
+                    if (!apiDefinedRpcs.contains(m.name())) {
+                      updatedMethods.add(
+                          m.toBuilder()
+                              .setMixedInApiName(serviceFullNameFn.apply(mixinService))
+                              .build());
+                    }
+                  });
           outputMixinServiceSet.add(mixinService);
         }
         services.set(i, originalService.toBuilder().setMethods(updatedMethods).build());

test/integration/BUILD.bazel

@@ -3,6 +3,8 @@ load(
     "java_gapic_assembly_gradle_pkg",
     "java_gapic_library",
     "java_gapic_test",
+    "java_grpc_library",
+    "java_proto_library",
 )
 load(
     "//:rules_bazel/java/integration_test.bzl",
@@ -19,7 +21,7 @@ package(default_visibility = ["//visibility:public"])
 INTEGRATION_TEST_LIBRARIES = [
     "asset",  # Basic case.
     "credentials",  # Check that the capital name edge case is handled.
-    "kms",  # Mixins.
+    "kms",  # Mixins, with an override in the proto file.
     "logging",  # Java package remapping in gapic.yaml.
     "redis",  # Has a gapic.yaml.
     "library",  # No gRPC service config.
@@ -156,18 +158,63 @@ java_gapic_assembly_gradle_pkg(
 )
 
 # KMS (for mixins).
+load("@rules_proto//proto:defs.bzl", "proto_library")
+load("@com_google_googleapis_imports//:imports.bzl", "proto_library_with_info")
+
+proto_library(
+    name = "kms_proto",
+    srcs = [
+        "apis/kms/v1/resources.proto",
+        "apis/kms/v1/service.proto",
+    ],
+    deps = [
+        "@com_google_googleapis//google/api:annotations_proto",
+        "@com_google_googleapis//google/api:client_proto",
+        "@com_google_googleapis//google/api:field_behavior_proto",
+        "@com_google_googleapis//google/api:resource_proto",
+        "@com_google_googleapis//google/iam/v1:iam_policy_proto",
+        "@com_google_googleapis//google/iam/v1:policy_proto",
+        "@com_google_protobuf//:duration_proto",
+        "@com_google_protobuf//:field_mask_proto",
+        "@com_google_protobuf//:struct_proto",
+        "@com_google_protobuf//:timestamp_proto",
+        "@com_google_protobuf//:wrappers_proto",
+    ],
+)
+
+proto_library_with_info(
+    name = "kms_proto_with_info",
+    deps = [
+        ":kms_proto",
+        "@com_google_googleapis//google/cloud:common_resources_proto",
+        "@com_google_googleapis//google/iam/v1:iam_policy_proto",
+        "@com_google_googleapis//google/iam/v1:policy_proto",
+    ],
+)
+
+java_proto_library(
+    name = "kms_java_proto",
+    deps = [":kms_proto"],
+)
+
+java_grpc_library(
+    name = "kms_java_grpc",
+    srcs = [":kms_proto"],
+    deps = [":kms_java_proto"],
+)
+
 java_gapic_library(
     name = "kms_java_gapic",
-    srcs = ["@com_google_googleapis//google/cloud/kms/v1:kms_proto_with_info"],
+    srcs = [":kms_proto_with_info"],
     grpc_service_config = "@com_google_googleapis//google/cloud/kms/v1:cloudkms_grpc_service_config.json",
     # For the IAM mixin.
-    service_yaml = "cloudkms_test_mixins_v1.yaml",
+    service_yaml = "apis/kms/v1/cloudkms_test_mixins_v1.yaml",
     test_deps = [
-        "@com_google_googleapis//google/cloud/kms/v1:kms_java_grpc",
+        ":kms_java_grpc",
         "@com_google_googleapis//google/iam/v1:iam_java_grpc",
     ],
     deps = [
-        "@com_google_googleapis//google/cloud/kms/v1:kms_java_proto",
+        ":kms_java_proto",
         "@com_google_googleapis//google/iam/v1:iam_java_proto",
     ],
 )