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-t09</groupId>
    <version>1.0</version>
  </parent>
  <modelVersion>4.0.0</modelVersion>
  <groupId>maven-t09</groupId>
  <artifactId>p2</artifactId>
  <packaging>pom</packaging>
  <name>p2</name>
  <version>1.0</version>
  <scm>
    <url>scm-url</url>
  </scm>

  <dependencies>

    <dependency>
      <groupId>maven-test</groupId>
      <artifactId>t09-a</artifactId>

    <artifactId>p0</artifactId>
    <groupId>maven-t10</groupId>
    <version>1.0</version>
  </parent>
  <modelVersion>4.0.0</modelVersion>
  <groupId>maven-t10</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>t10-a</artifactId>

<project>
  <modelVersion>4.0.0</modelVersion>
  <groupId>maven-test</groupId>
  <artifactId>scope-compile</artifactId>
  <version>1.0</version>
  <dependencies>

    <dependency>
      <groupId>maven-test-compile</groupId>
      <artifactId>scope-default</artifactId>
      <version>1.0</version>
    </dependency>

    <dependency>
      <groupId>maven-test-compile</groupId>
      <artifactId>scope-test</artifactId>

  <parent>
    <groupId>org.apache.maven</groupId>
    <artifactId>maven-api</artifactId>
    <version>4.0.0-beta-6-SNAPSHOT</version>
  </parent>

  <artifactId>maven-api-cli</artifactId>
  <name>Maven 4 API :: CLI</name>
  <description>Maven 4 API - CLI.</description>

  <dependencies>
    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-api-meta</artifactId>

    <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>

      <artifactId>maven-compat</artifactId>
    </dependency>

    <dependency>
      <groupId>commons-cli</groupId>
      <artifactId>commons-cli</artifactId>
    </dependency>
    <dependency>
      <groupId>org.apache.maven.wagon</groupId>
      <artifactId>wagon-http</artifactId>
    </dependency>
    <dependency>
      <groupId>org.apache.maven.wagon</groupId>

  <dependencies>
    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-api-meta</artifactId>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.codehaus.modello</groupId>
        <artifactId>modello-maven-plugin</artifactId>
        <executions>
          <execution>

    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-api-model</artifactId>
    </dependency>
    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-api-core</artifactId>
    </dependency>
    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-api-di</artifactId>
    </dependency>
  </dependencies>

<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>test?</groupId>
          <artifactId>*</artifactId>
        </exclusion>