<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>
      </exclusions>

import org.apache.maven.artifact.versioning.ArtifactVersion;
import org.apache.maven.artifact.versioning.DefaultArtifactVersion;
import org.apache.maven.artifact.versioning.OverConstrainedVersionException;
import org.apache.maven.artifact.versioning.VersionRange;

/**
 */
public class DefaultArtifact implements Artifact {
    private String groupId;

    private String artifactId;

-->

<project>
  <modelVersion>4.0.0</modelVersion>
  <artifactId>aid</artifactId>
  <groupId>gid</groupId>
  <version>0.1</version>

  <dependencies>
    <dependency>
      <groupId>test</groupId>
      <artifactId>a</artifactId>
      <version>0.2</version>
    </dependency>
    <dependency>
      <groupId>test</groupId>
      <artifactId>b</artifactId>
      <version>0.2</version>
      <scope>compile</scope>

<project>
  <modelVersion>4.0.0</modelVersion>
  <artifactId>aid</artifactId>
  <groupId>gid</groupId>
  <version>0.1</version>

  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>test</groupId>
        <artifactId>a</artifactId>
        <version>0.2</version>
      </dependency>
      <dependency>
        <groupId>test</groupId>
        <artifactId>b</artifactId>
        <version>0.2</version>

					<artifactId>javax.annotation-api</artifactId>
				</exclusion>
				<exclusion>
					<groupId>net.java.dev.jna</groupId>
					<artifactId>jna</artifactId>
				</exclusion>
				<exclusion>
					<groupId>org.apache.httpcomponents</groupId>
					<artifactId>httpmime</artifactId>
				</exclusion>
				<exclusion>
					<groupId>org.slf4j</groupId>
					<artifactId>jcl-over-slf4j</artifactId>

    }

    /**
     * Gets the artifacts that make up the plugin's class realm, excluding artifacts shadowed by the Maven core realm
     * like {@code maven-project}.
     *
     * @return The plugin artifacts, never {@code null}.
     */
    public List<Artifact> getArtifacts() {
        return artifacts;
    }

    public void setArtifacts(List<Artifact> artifacts) {
        this.artifacts = artifacts;

      <artifactId>maven-api-spi</artifactId>
    </dependency>
    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-api-core</artifactId>
    </dependency>

    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-xml</artifactId>
    </dependency>
    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-support</artifactId>
    </dependency>

specific language governing permissions and limitations
under the License.
-->

<project>
  <modelVersion>4.0.0</modelVersion>
  <artifactId>aid</artifactId>
  <groupId>gid</groupId>
  <version>0.1</version>

  <dependencies>
    <dependency>
      <groupId>test</groupId>
      <artifactId>a</artifactId>
      <version>0.2</version>
      <scope>system</scope>

 the Maven Repository Metadata file contains 3 different sets of metadata:

 [[1]] in a "groupId" directory: a "groupId" directory may contain Maven plugins artifacts, which are described in metadata's <<<plugins>>> element,

 [[2]] in a "groupId/artifactId" directory: metadata describes <<<groupId>>>, <<<artifactId>>> and <<<versioning>>> element that

    }

    public static Map<String, Artifact> artifactMapByVersionlessId(Collection<Artifact> artifacts) {
        Map<String, Artifact> artifactMap = new LinkedHashMap<>();

        if (artifacts != null) {
            for (Artifact artifact : artifacts) {
                artifactMap.put(versionlessKey(artifact), artifact);
            }
        }

        return artifactMap;
    }