gRPC maven is not generating stub classes in the target folder

Question

It used to work fine, and I'm not sure what changed that I don't see the generated stubs anymore.

I also see archive-temp in the target folder, not sure why it's only appearing now.

Any life cycle events compile the project fine without any errors, but no stubs whatsoever.

Here's my maven file.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.mycompany</groupId>
    <artifactId>Customer</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>

All life cycle events like clean, package

Properties

    <properties>
        <maven.compiler.target>1.8</maven.compiler.target>
        <maven.compiler.source>1.8</maven.compiler.source>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>

        <grpc.version>1.22.1</grpc.version>
        <os.plugin.version>1.5.0.Final</os.plugin.version>
        <protobuf.plugin.version>0.6.1</protobuf.plugin.version>
        <protoc.version>3.9.0</protoc.version>
    </properties>

Dependencies

     <dependencies>
        <dependency>
            <groupId>com.google.protobuf</groupId>
            <artifactId>protobuf-java</artifactId>
            <version>${protoc.version}</version>
        </dependency>
        <dependency>
            <groupId>io.grpc</groupId>
            <artifactId>grpc-netty-shaded</artifactId>
            <version>${grpc.version}</version>
        </dependency>
        <dependency>
            <groupId>io.grpc</groupId>
            <artifactId>grpc-protobuf</artifactId>
            <version>${grpc.version}</version>
        </dependency>
        <dependency>
            <groupId>io.grpc</groupId>
            <artifactId>grpc-stub</artifactId>
            <version>${grpc.version}</version>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>io.grpc</groupId>
                <artifactId>grpc-bom</artifactId>
                <version>${grpc.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

Build Plugins <build>

        <plugins>
            <plugin>
                <groupId>org.xolstice.maven.plugins</groupId>
                <artifactId>protobuf-maven-plugin</artifactId>
                <version>0.6.1</version>
            </plugin>
            <plugin>
                <artifactId>maven-assembly-plugin</artifactId>
                <configuration>
                    <archive>
                        <manifest>
                            <mainClass>org.puremvc.java.multicore.demos.microservice.employeeadmin.department.Service</mainClass>
                        </manifest>
                    </archive>
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependencies</descriptorRef>
                    </descriptorRefs>
                </configuration>
                <executions>
                    <execution>
                        <id>make-assembly</id> <!-- this is used for inheritance merges -->
                        <phase>package</phase> <!-- bind to the packaging phase -->
                        <goals>
                            <goal>single</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>

Extensions and Plugin Management

        <extensions>
            <extension>
                <groupId>kr.motd.maven</groupId>
                <artifactId>os-maven-plugin</artifactId>
                <version>1.5.0.Final</version>
            </extension>
        </extensions>
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>kr.motd.maven</groupId>
                    <artifactId>os-maven-plugin</artifactId>
                    <version>${os.plugin.version}</version>
                </plugin>
                <plugin>
                    <groupId>org.xolstice.maven.plugins</groupId>
                    <artifactId>protobuf-maven-plugin</artifactId>
                    <version>${protobuf.plugin.version}</version>
                    <configuration>
                        <protocArtifact>com.google.protobuf:protoc:${protoc.version}:exe:${os.detected.classifier}</protocArtifact>
                        <pluginId>grpc-java</pluginId>
                        <pluginArtifact>io.grpc:protoc-gen-grpc-java:${grpc.version}:exe:${os.detected.classifier}</pluginArtifact>
                    </configuration>
                    <executions>
                        <execution>
                            <goals>
                                <goal>compile</goal>
                                <goal>compile-custom</goal>
                            </goals>
                        </execution>
                    </executions>
                </plugin>
            </plugins>
        </pluginManagement>

    </build>
</project>

Answer 1

Building with your pom.xml produces:

[INFO] --- protobuf-maven-plugin:0.6.1:compile (default) @ Customer ---
[INFO] Skipping mojo execution for project with packaging type 'pom'
[INFO] 
[INFO] --- protobuf-maven-plugin:0.6.1:compile-custom (default) @ Customer ---
[INFO] Skipping mojo execution for project with packaging type 'pom'

Changing the packaging from pom to jar seems to fix the problem, as the stub is visible in target/generated-sources/protobuf/grpc-java after a mvn compile .

    <groupId>com.mycompany</groupId>
    <artifactId>Customer</artifactId>
    <packaging>jar</packaging> <!-- was 'pom' -->
    <version>1.0-SNAPSHOT</version>