<extensions>
      <extension>
        <groupId>org.apache.maven.its.mng3899</groupId>
        <artifactId>b</artifactId>
        <version>0.1</version>
      </extension>
      <extension>
        <!-- project extensions should override inherited extension with equal gid:aid -->
        <groupId>org.apache.maven.its.mng3899</groupId>
        <artifactId>a</artifactId>
        <version>0.2</version>

  <modelVersion>4.0.0</modelVersion>

  <parent>
    <groupId>org.apache.maven</groupId>
    <artifactId>maven</artifactId>
    <version>4.0.0-beta-4-SNAPSHOT</version>
  </parent>

  <artifactId>maven-artifact</artifactId>

  <name>Maven Artifact</name>

  <dependencies>
    <dependency>
      <groupId>org.junit.jupiter</groupId>
      <artifactId>junit-jupiter-api</artifactId>
      <scope>test</scope>

    }

    private void validateIdentity() {
        if (empty(groupId)) {
            throw new InvalidArtifactRTException(
                    groupId, artifactId, getVersion(), type, "The groupId cannot be empty.");
        }

        if (artifactId == null) {
            throw new InvalidArtifactRTException(
                    groupId, artifactId, getVersion(), type, "The artifactId cannot be empty.");
        }

<project>
    <modelVersion>4.0.0</modelVersion>
    <groupId>org.sonatype.nexus</groupId>
    <artifactId>nexus</artifactId>
    <version>1.3.0-SNAPSHOT</version>
    <build>
        <plugins>
            <plugin>
                <groupId>org.codehaus.modello</groupId>
                <artifactId>modello-maven-plugin</artifactId>
                <version>1.0-alpha-21</version>
                <executions>
                    <execution>

    <groupId>util</groupId>
    <artifactId>util</artifactId>
    <version>2.5</version>
    <packaging>jar</packaging>

    <dependencies>
        <dependency>
            <groupId>commons-lang</groupId>
            <artifactId>commons-lang</artifactId>
            <version>2.6</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>

      <build>
        <pluginManagement>
          <plugins>
            <plugin>
              <groupId>org.apache.maven.its.plugins</groupId>
              <artifactId>maven-it-plugin-class-loader</artifactId>
              <dependencies>
                <dependency>
                  <groupId>org.apache.maven.its.mng2174</groupId>
                  <artifactId>a</artifactId>
                  <version>0.1</version>

public class MavenDependencyKey {
    private static final String KEY_SEPARATOR = ":";
    private final String groupId;
    private final String artifactId;
    private final String type;
    private final String classifier;

    public MavenDependencyKey(String groupId, String artifactId, String type, String classifier) {
        this.groupId = groupId;
        this.artifactId = artifactId;
        this.type = type;
        this.classifier = classifier;

    }

    private Plugin createPlugin(String groupId, String artifactId, String version) {
        Plugin plugin = new Plugin();
        plugin.setGroupId(groupId);
        plugin.setArtifactId(artifactId);
        plugin.setVersion(version);
        return plugin;
    }

    private Extension createExtension(String groupId, String artifactId, String version) {
        Extension extension = new Extension();

<project>
  <modelVersion>4.0.0</modelVersion>
  <packaging>pom</packaging>
  <groupId>org.gradle</groupId>
  <artifactId>test</artifactId>
  <version>0</version>

  <modules>
    <module>commons</module>
  </modules>
</project>
"""

        temp.file("commons/pom.xml").text = """\
<project>
  <parent>
    <groupId>org.gradle</groupId>
    <artifactId>test</artifactId>
    <version>0</version>
  </parent>

    <parent>
        <groupId>org.example</groupId>
        <artifactId>parent</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <relativePath>./parent-pom.xml</relativePath>
    </parent>

    <artifactId>child</artifactId>
    <packaging>jar</packaging>

    <build>
        <plugins>
            <plugin>
                <groupId>${codehaus.groupId}</groupId>