this.artifactId = (artifactId != null) ? artifactId : "";
        this.version = (version != null) ? version : "";
    }

    /**
     * Creates a new exception with specified cause
     *
     * @param cause
     * @param groupId
     * @param artifactId
     * @param version
     */
    public UnresolvableModelException(Throwable cause, String groupId, String artifactId, String version) {

    <artifactId>p0</artifactId>
    <groupId>maven-t04</groupId>
    <version>1.0</version>
  </parent>
  <modelVersion>4.0.0</modelVersion>
  <groupId>maven-t04</groupId>
  <artifactId>p1</artifactId>
  <packaging>pom</packaging>
  <name>p1</name>
  <version>1.0</version>
  <scm>
    <url>scm-url</url>
  </scm>

  <dependencies>

    <dependency>
      <groupId>maven-test</groupId>
      <artifactId>t04-a</artifactId>

        this.classLoadingStrategy = classLoadingStrategy;
    } // -- void setClassLoadingStrategy( String )

    /**
     * Set the group ID of the extension's artifact.
     *
     * @param groupId a groupId object.
     */
    public void setGroupId(String groupId) {
        this.groupId = groupId;
    } // -- void setGroupId( String )

    /**
     * Set the version of the extension.
     *

    <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>

  <groupId>maven-test</groupId>
  <artifactId>t08-b</artifactId>
  <packaging>jar</packaging>
  <version>1.1</version>
  <dependencies>
    <dependency>
      <groupId>maven-test</groupId>
      <artifactId>t08-c</artifactId>
      <version>1.0</version>
      <type>jar</type>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>maven-test</groupId>

<project>
  <modelVersion>4.0.0</modelVersion>
  <artifactId>foo</artifactId>
  <groupId>foo</groupId>
  <version>99.44</version>
  <packaging>jar</packaging>

  <dependencies>
    <dependency>
      <groupId>gid</groupId>
      <artifactId>aid</artifactId>
      <version>1.0</version>
      <exclusions>
        <exclusion>
          <groupId></groupId>
        </exclusion>
      </exclusions>
    </dependency>

<project>
  <modelVersion>4.0.0</modelVersion>
  <groupId>maven-test</groupId>
  <artifactId>t05-a</artifactId>
  <packaging>jar</packaging>
  <version>2.0</version>
  <repositories>
    <repository>
      <id>central</id>
      <name>Fake Maven Central Repository</name>
      <url>file://dummy</url>
    </repository>
  </repositories>
  <dependencies>
    <dependency>
      <groupId>maven-test</groupId>
      <artifactId>t05-b</artifactId>

    @Nonnull
    default Artifact create(
            @Nonnull Session session, String groupId, String artifactId, String version, String extension) {
        return create(ArtifactFactoryRequest.build(session, groupId, artifactId, version, extension));
    }

    @Nonnull
    default Artifact create(
            @Nonnull Session session,
            String groupId,
            String artifactId,
            String version,

    <modelVersion>4.0.0</modelVersion>

    <groupId>test</groupId>
    <artifactId>test</artifactId>
    <version>0.1-SNAPSHOT</version>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>test</groupId>
                <artifactId>other</artifactId>
                <version>0.1-SNAPSHOT</version>

    <modelVersion>4.0.0</modelVersion>

    <groupId>org.junit</groupId>
    <artifactId>bom</artifactId>
    <version>0.2</version>
    <packaging>pom</packaging>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.junit</groupId>
                <artifactId>junit</artifactId>
                <version>0.2</version>