Download of Protobuf in Vraptor3

gistfile1.java

//Controller
@Get
public final Download authenticate() {

      AuthenticationProto.Authentication proto = AuthenticationProto.Authentication.newBuilder()
                                                                    .setToken("token") //sample code
                                                                    .build();
      return new ProtoDownload(proto);
}

//ProtoDownload.java

package com.xpto.util;

import br.com.caelum.vraptor.interceptor.download.ByteArrayDownload;
import br.com.caelum.vraptor.interceptor.download.Download;
import com.google.protobuf.GeneratedMessage;

import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class ProtoDownload implements Download {

    private final GeneratedMessage proto;

    public ProtoDownload(final GeneratedMessage proto) {

        this.proto = proto;
    }

    @Override
    public void write(final HttpServletResponse response) throws IOException {

        byte[] bytes = this.proto.toByteArray();

        ByteArrayDownload download = new ByteArrayDownload(bytes, "application/x-protobuf", this.proto.getClass().getSimpleName(), true);

        download.write(response);
    }
}