How can I generate Scala files instead of Java files from from Protobuf

Question

My aim is to use akka-grpc in my project. By using the walkthrough, https://developer.lightbend.com/docs/akka-grpc/current/client/walkthrough.html I tried to generate Scala files. However, whenever I build the project (by mvn clean package) it generates Java files instead of Scala files. Is there a way to generate Scala files? I already tried converting Java to Scala but it did not work. Here is my proto file (the same one in the walkthrough):

syntax = "proto3";

option java_multiple_files = true;
option java_package = "example.myapp.helloworld.grpc";
option java_outer_classname = "HelloWorldProto";

package helloworld;

// The greeting service definition.
service GreeterService {
    // Sends a greeting
    rpc SayHello (HelloRequest) returns (HelloReply) {}

    rpc ItKeepsTalking (stream HelloRequest) returns (HelloReply) {}

    rpc ItKeepsReplying (HelloRequest) returns (stream HelloReply) {}

    rpc StreamHellos (stream HelloRequest) returns (stream HelloReply) {}
}

// The request message containing the user's name.
message HelloRequest {
    string name = 1;
}

// The response message containing the greetings
message HelloReply {
    string message = 1;
}

Answer 1

You should specify this in your maven configuration. From the docs:

<plugin>
    <groupId>com.lightbend.akka.grpc</groupId>
    <artifactId>akka-grpc-maven-plugin</artifactId>
    <version>${akka.grpc.version}</version>
    <configuration>
      <language>Scala</language>
      <generateClient>false</generateClient>
      <generateServer>true</generateServer>
    </configuration>
</plugin>