* under the License.
 */
package org.apache.maven.project;

import org.apache.maven.artifact.Artifact;

/**
 * This exception is thrown if an application attempts to attach
 * two of the same artifacts to a single project.
 *
 * TODO Make this a checked exception, and modify the API of MavenProjectHelper.
 * Currently, this modification would create compatibility problems for existing plugins.

import org.apache.maven.api.Service;
import org.apache.maven.api.Session;
import org.apache.maven.api.annotations.Experimental;

/**
 * Resolves the artifact, i.e download the file when required and attach it to the artifact
 *
 * @since 4.0.0
 */
@Experimental
public interface ArtifactResolver extends Service {

    /**
     * @param request {@link ArtifactResolverRequest}

            </configuration>
          </execution>
          <execution>
            <id>install</id>
            <phase>generate-sources</phase>
            <goals>
              <goal>set</goal>
              <goal>attach-pom</goal>
              <goal>install</goal>
            </goals>
            <configuration>
              <mainFile>dependency-1.jar</mainFile>
            </configuration>
          </execution>

import org.apache.maven.artifact.metadata.ArtifactMetadata;
import org.apache.maven.artifact.repository.ArtifactRepository;
import org.apache.maven.artifact.repository.metadata.RepositoryMetadataStoreException;

/**
 * Attach a POM to an artifact.
 *
 */
@Deprecated
public class ProjectArtifactMetadata extends AbstractArtifactMetadata {
    private final File file;

    public ProjectArtifactMetadata(Artifact artifact) {

      </plugin>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>build-helper-maven-plugin</artifactId>
        <executions>
          <execution>
            <goals>
              <goal>attach-artifact</goal>
            </goals>
            <configuration>
              <artifacts>
                <artifact>
                  <file>${basedir}/src/main/mdo/maven.mdo</file>
                  <type>mdo</type>

    }

    public List<ArtifactVersion> getAvailableVersions() {
        return parent.getAvailableVersions();
    }

    public void setAvailableVersions(List<ArtifactVersion> availableVersions) {
        throw new UnsupportedOperationException("Cannot change the version information for an attached artifact."

        InternalMavenSession session = ((DefaultProject) project).getSession();
        Collection<Artifact> attached = map(
                getMavenProject(project).getAttachedArtifacts(),
                a -> session.getArtifact(RepositoryUtils.toArtifact(a)));
        return Collections.unmodifiableCollection(attached);
    }

    @Override
    public Collection<Artifact> getAllArtifacts(Project project) {

        artifact.setFile(artifactFile);
        artifact.setResolved(true);

        attachArtifact(project, artifact);
    }

    /**
     * Add an attached artifact or replace the file for an existing artifact.
     *
     * @see MavenProject#addAttachedArtifact(org.apache.maven.artifact.Artifact)
     * @param project project reference.

foreach configuration element:
 - if read only and being set squawk

 - find the parameter
 - get value from expression or default
 - if required and null squawk

      <configuration>
        <attached implementation="boolean" default-value="true"/>
        <localRepository implementation="org.apache.maven.artifact.repository.ArtifactRepository">${localRepository}</localRepository>

    Optional<Path> getPath(Project project);

    /**
     * Returns an immutable collection of attached artifacts for given project.
     */
    @Nonnull
    Collection<Artifact> getAttachedArtifacts(Project project);

    /**
     * Returns project's all artifacts as immutable collection. The list contains all artifacts, even the attached ones,