Provide a way to ignore json_name in HTTP/JSON transcoding

Motivation:

There is a bug in protoc that always adds json_name to the descriptor.
This happens by default when compiling proto files in Bazel.
To mitigate this bug, I propose to add `HttpJsonTranscodingQueryParamMatchRule.IGORE_JSON`
to forcibliy ignore json_name when matching query params or path
variables.

Modifications:

- Add `HttpJsonTranscodingQueryParamMatchRule.INGORE_JSON`
  - If enabled, the `json_name` field option is ignored.

Result:

- Fixes #5890
- You can now ignore the `json_name` field option when trancoding
  HTTP/JSON to gRPC messages.

grpc/src/main/java/com/linecorp/armeria/server/grpc/HttpJsonTranscodingQueryParamMatchRule.java

@@ -42,5 +42,14 @@ public enum HttpJsonTranscodingQueryParamMatchRule {
     /**
      * Uses the original fields in .proto files to match {@link QueryParams} of an {@link HttpRequest}.
      */
-    ORIGINAL_FIELD
+    ORIGINAL_FIELD,
+    /**
+     * Ignore the {@code json_name} field option in .proto files and uses either the original field name or the
+     * lowerCamelCase field name instead.
+     *
+     * <p>This option is useful when the protoc compiler always populates the {@code json_name} in the
+     * descriptor. See <a href="https://github.com/protocolbuffers/protobuf/issues/5587">protobuf/issues/5587</a>
+     * for more details.
+     */
+    IGNORE_JSON_NAME
 }

grpc/src/main/java/com/linecorp/armeria/server/grpc/HttpJsonTranscodingService.java

@@ -20,6 +20,7 @@
 import static com.google.common.collect.ImmutableList.toImmutableList;
 import static com.google.common.collect.ImmutableMap.toImmutableMap;
 import static com.google.common.collect.ImmutableSet.toImmutableSet;
+import static com.linecorp.armeria.server.grpc.HttpJsonTranscodingQueryParamMatchRule.IGNORE_JSON_NAME;
 import static com.linecorp.armeria.server.grpc.HttpJsonTranscodingQueryParamMatchRule.LOWER_CAMEL_CASE;
 import static java.util.Objects.requireNonNull;
 
@@ -172,16 +173,20 @@ static GrpcService of(GrpcService delegate, HttpJsonTranscodingOptions httpJsonT
                     continue;
                 }
 
+                // TODO(ikhoon): Extract the build-time code into a separate class such as
+                //               HttpJsonTranscodingServiceBuilder or HttpJsonTranscodingSpecGenerator
+                final Set<HttpJsonTranscodingQueryParamMatchRule> queryParamMatchRules =
+                        httpJsonTranscodingOptions.queryParamMatchRules();
+                final boolean ignoreJsonName = queryParamMatchRules.contains(IGNORE_JSON_NAME);
                 final Route route = routeAndVariables.getKey();
                 final List<PathVariable> pathVariables = routeAndVariables.getValue();
                 final Map<String, Field> originalFields =
                         buildFields(methodDesc.getInputType(), ImmutableList.of(), ImmutableSet.of(),
-                                    false);
+                                    false, ignoreJsonName);
                 final Map<String, Field> camelCaseFields;
-                if (httpJsonTranscodingOptions.queryParamMatchRules().contains(LOWER_CAMEL_CASE)) {
-                    camelCaseFields =
-                            buildFields(methodDesc.getInputType(), ImmutableList.of(), ImmutableSet.of(),
-                                        true);
+                if (queryParamMatchRules.contains(LOWER_CAMEL_CASE)) {
+                    camelCaseFields = buildFields(methodDesc.getInputType(), ImmutableList.of(),
+                                                  ImmutableSet.of(), true, ignoreJsonName);
                 } else {
                     camelCaseFields = ImmutableMap.of();
                 }
@@ -312,7 +317,7 @@ static Entry<Route, List<PathVariable>> toRouteAndPathVariables(HttpRule httpRul
     private static Map<String, Field> buildFields(Descriptor desc,
                                                   List<String> parentNames,
                                                   Set<Descriptor> visitedTypes,
-                                                  boolean useCamelCaseKeys) {
+                                                  boolean useCamelCaseKeys, boolean ignoreJsonName) {
         final StringJoiner namePrefixJoiner = new StringJoiner(".");
         parentNames.forEach(namePrefixJoiner::add);
         final String namePrefix = namePrefixJoiner.length() == 0 ? "" : namePrefixJoiner.toString() + '.';
@@ -322,7 +327,7 @@ private static Map<String, Field> buildFields(Descriptor desc,
             final JavaType type = field.getJavaType();
             final String fieldName;
 
-            if (field.toProto().hasJsonName()) {
+            if (!ignoreJsonName && field.toProto().hasJsonName()) {
                 fieldName = field.toProto().getJsonName();
             } else {
                 if (useCamelCaseKeys) {
@@ -369,7 +374,7 @@ private static Map<String, Field> buildFields(Descriptor desc,
                                                                .addAll(visitedTypes)
                                                                .add(field.getMessageType())
                                                                .build(),
-                                                   useCamelCaseKeys));
+                                                   useCamelCaseKeys, ignoreJsonName));
                     } catch (RecursiveTypeException e) {
                         if (e.recursiveTypeDescriptor() != field.getMessageType()) {
                             // Re-throw the exception if it is not caused by my field.

it/grpc-json-name/build.gradle

@@ -0,0 +1,4 @@
+dependencies {
+    implementation project(':grpc')
+    testImplementation libs.javax.annotation
+}

it/grpc-json-name/src/proto/hello.proto.original

@@ -0,0 +1,14 @@
+syntax = "proto3";
+
+package hello.v1;
+option java_package = "testing.grpc.jsonname";
+
+option java_multiple_files = true;
+
+message HelloRequest {
+  string name_input = 1;
+}
+
+message HelloReply {
+  string message = 1;
+}

it/grpc-json-name/src/proto/hello_service.proto.original

@@ -0,0 +1,18 @@
+syntax = "proto3";
+
+package hello.service.v1;
+
+import "hello/v1/hello.proto";
+import "google/api/annotations.proto";
+
+option java_package = "testing.grpc.jsonname";
+option java_multiple_files = true;
+
+
+service HelloService {
+  rpc Hello (hello.v1.HelloRequest) returns (hello.v1.HelloReply){
+    option (google.api.http) = {
+      get: "/v1/hello/{name_input}"
+    };
+  }
+}

it/grpc-json-name/src/test/java/com/linecorp/armeria/server/grpc/jsonname/GrpcTranscodingJsonNameTest.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2025 LINE Corporation
+ *
+ * LINE Corporation licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+
+package com.linecorp.armeria.server.grpc.jsonname;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import com.linecorp.armeria.client.BlockingWebClient;
+import com.linecorp.armeria.common.AggregatedHttpResponse;
+import com.linecorp.armeria.common.HttpStatus;
+import com.linecorp.armeria.server.ServerBuilder;
+import com.linecorp.armeria.server.grpc.GrpcService;
+import com.linecorp.armeria.server.grpc.HttpJsonTranscodingOptions;
+import com.linecorp.armeria.server.grpc.HttpJsonTranscodingQueryParamMatchRule;
+import com.linecorp.armeria.testing.junit5.server.ServerExtension;
+
+import static net.javacrumbs.jsonunit.fluent.JsonFluentAssert.assertThatJson;
+import static org.assertj.core.api.Assertions.assertThat;
+
+class GrpcTranscodingJsonNameTest {
+
+    @RegisterExtension
+    static ServerExtension server = new ServerExtension() {
+        @Override
+        protected void configure(ServerBuilder sb) {
+            final HttpJsonTranscodingOptions options =
+                    HttpJsonTranscodingOptions.builder()
+                                              .queryParamMatchRules(
+                                                      HttpJsonTranscodingQueryParamMatchRule.IGNORE_JSON_NAME)
+                                              .build();
+            final GrpcService grpcService = GrpcService.builder()
+                                                       .addService(new HelloService())
+                                                       .enableHttpJsonTranscoding(options)
+                                                       .build();
+            sb.service(grpcService);
+        }
+    };
+
+    @Test
+    void shouldIgnoreJsonNameOption() {
+        final BlockingWebClient client = server.blockingWebClient();
+        final AggregatedHttpResponse response = client.get("/v1/hello/Armeria");
+        assertThat(response.status()).isEqualTo(HttpStatus.OK);
+        assertThatJson(response.contentUtf8())
+                .isEqualTo("{\"message\":\"Hello, Armeria!\"}");
+    }
+}

it/grpc-json-name/src/test/java/com/linecorp/armeria/server/grpc/jsonname/HelloService.java

@@ -0,0 +1,18 @@
+package com.linecorp.armeria.server.grpc.jsonname;
+
+import io.grpc.stub.StreamObserver;
+import testing.grpc.jsonname.HelloReply;
+import testing.grpc.jsonname.HelloRequest;
+import testing.grpc.jsonname.HelloServiceGrpc;
+
+public class HelloService extends HelloServiceGrpc.HelloServiceImplBase {
+
+    @Override
+    public void hello(HelloRequest req, StreamObserver<HelloReply> responseObserver) {
+        HelloReply reply = HelloReply.newBuilder()
+                .setMessage("Hello, " + req.getNameInput() + '!')
+                .build();
+        responseObserver.onNext(reply);
+        responseObserver.onCompleted();
+    }
+}