RpcChannel instead of io.grpc.Channel

I'm having issues with gRPC Java protobuf code generation. When I use the protobuf-maven-plugin to generate Java classes from my .proto files, it creates deprecated classes that use RpcChannel instead of io.grpc.Channel. I'm using protobuf-maven-plugin version 0.6.1, protoc version 3.23.2, and grpc-java version 1.55.1.

Here are the versions I'm using:

Apache Maven 3.9.2
grpc-netty-shaded 1.55.1
grpc-protobuf 1.55.1
grpc-stub 1.55.1
protobuf-java 3.23.2
JDK 11.0.19
macOS 13.4 on Apple Silicon architecture
My .proto file looks like this:

syntax = "proto3";
package agent;

option java_multiple_files = true;
option java_generic_services = true;
option java_package = "grpc";
option java_outer_classname = "AgentServerProto";
option objc_class_prefix = "Utm";

// Service and message definitions omitted for brevity...

Despite setting option java_generic_services = true;, the generated Java code does not contain any of the expected service implementation base classes, like PanelServiceImplBase for my service definition.

Even after updating the protoc version and following the appropriate steps for installation, I'm still encountering this issue.

Could someone provide guidance on what could be causing this issue and how to resolve it? Thank you in advance.

I initially encountered the problem when trying to generate gRPC Java classes using the protobuf-maven-plugin. My expectation was to have classes generated that are up-to-date, using io.grpc.Channel instead of the deprecated RpcChannel. I was also expecting to see the service implementation base classes generated based on my .proto file.

I even tried different versions of the protobuf-maven-plugin, java SDK, generate the code from a windows laptop

option java_generic_services = true is not related to gRPC. That's why you are getting RpcChannel. You can remove it.

The gRPC code generation is separate from protoc, using a custom plugin named protoc-gen-grpc-java. To use it you need the compile-custom goal for protobuf-maven-plugin.

From the grpc-java README:

<build>
  <plugins>
    <plugin>
      <groupId>org.xolstice.maven.plugins</groupId>
      <artifactId>protobuf-maven-plugin</artifactId>
      <version>0.6.1</version>
      <configuration>
        <protocArtifact>com.google.protobuf:protoc:3.21.7:exe:${os.detected.classifier}</protocArtifact>
        <!-- IMPORTANT: -->
        <pluginId>grpc-java</pluginId>
        <pluginArtifact>io.grpc:protoc-gen-grpc-java:1.54.1:exe:${os.detected.classifier}</pluginArtifact>
      </configuration>
      <executions>
        <execution>
          <goals>
            <goal>compile</goal>
            <goal>compile-custom</goal> <!-- IMPORTANT -->
          </goals>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>