From f5f8f1c0360ad8c59e18560bd5883833bdeb1422 Mon Sep 17 00:00:00 2001
From: halo <dongjin778@naver.com>
Date: Wed, 10 Jun 2026 08:38:16 +0900
Subject: [PATCH] docs: document required dependencies for JsonToGrpc filter
 (GH-3424)

The JsonToGrpc filter depends on several optional libraries (jackson-dataformat-protobuf,
grpc-netty, grpc-protobuf, grpc-stub, protobuf-java-util) that must be added explicitly.
Without them, a NoClassDefFoundError is thrown at runtime when a request hits the route.
Added a "Required Dependencies" section with Maven and Gradle examples.

Closes gh-3424

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 .../jsontogrpc-factory.adoc                   | 47 +++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/docs/modules/ROOT/pages/spring-cloud-gateway-server-webflux/gatewayfilter-factories/jsontogrpc-factory.adoc b/docs/modules/ROOT/pages/spring-cloud-gateway-server-webflux/gatewayfilter-factories/jsontogrpc-factory.adoc
index b5ce622e1..229bb8a89 100644
--- a/docs/modules/ROOT/pages/spring-cloud-gateway-server-webflux/gatewayfilter-factories/jsontogrpc-factory.adoc
+++ b/docs/modules/ROOT/pages/spring-cloud-gateway-server-webflux/gatewayfilter-factories/jsontogrpc-factory.adoc
@@ -3,6 +3,53 @@
 
 The JSONToGRPC GatewayFilter Factory converts a JSON payload to a gRPC request.
 
+[[jsontogrpc-dependencies]]
+== Required Dependencies
+
+The `JsonToGrpc` filter depends on several optional libraries that are *not* included by default.
+You must add them explicitly to your project:
+
+.Maven
+[source,xml]
+----
+<dependency>
+    <groupId>tools.jackson.dataformat</groupId>
+    <artifactId>jackson-dataformat-protobuf</artifactId>
+</dependency>
+<dependency>
+    <groupId>io.grpc</groupId>
+    <artifactId>grpc-netty</artifactId>
+</dependency>
+<dependency>
+    <groupId>io.grpc</groupId>
+    <artifactId>grpc-protobuf</artifactId>
+</dependency>
+<dependency>
+    <groupId>io.grpc</groupId>
+    <artifactId>grpc-stub</artifactId>
+</dependency>
+<dependency>
+    <groupId>com.google.protobuf</groupId>
+    <artifactId>protobuf-java-util</artifactId>
+</dependency>
+----
+
+.Gradle
+[source,groovy]
+----
+implementation 'tools.jackson.dataformat:jackson-dataformat-protobuf'
+implementation 'io.grpc:grpc-netty'
+implementation 'io.grpc:grpc-protobuf'
+implementation 'io.grpc:grpc-stub'
+implementation 'com.google.protobuf:protobuf-java-util'
+----
+
+[WARNING]
+====
+If any of these dependencies are missing you will see a `NoClassDefFoundError` at runtime (for example, `com/fasterxml/jackson/dataformat/protobuf/ProtobufFactory`) when a request hits the route.
+The versions are managed by the Spring Cloud Gateway BOM, so no version attributes are needed when using the BOM.
+====
+
 The filter takes the following arguments:
 
 * `service`: Short name of the service that handles the request.