printErrors(result);

        Iterator<Artifact> i = result.getArtifacts().iterator();
        assertEquals(n, i.next(), "n should be first");
        assertEquals(m, i.next(), "m should be second");

        // inverse order
        set = new LinkedHashSet<>();
        set.add(m);
        set.add(n);

        // POMs are always returned from the file system
        if ("pom".equals(artifact.getExtension())) {
            return project.getFile();
        }

        // First check in the project local repository
        File packagedArtifactFile = findInProjectLocalRepository(artifact);
        if (packagedArtifactFile != null
                && packagedArtifactFile.exists()

                    pluginDescriptor.getPlugin(),
                    "The plugin " + pluginDescriptor.getId() + " has unmet prerequisites: " + messages,
                    prerequisiteExceptions.get(0));
            // the first exception is added as cause, all other ones as suppressed exceptions
            prerequisiteExceptions.stream().skip(1).forEach(pie::addSuppressed);
            throw pie;
        }
    }

    @Override

        // We want to send the root artifact back in the result but we need to do this after the other dependencies
        // have been resolved.
        if (request.isResolveRoot()) {
            // Add the root artifact (as the first artifact to retain logical order of class path!)
            Set<Artifact> allArtifacts = new LinkedHashSet<>();
            allArtifacts.add(rootArtifact);
            allArtifacts.addAll(result.getArtifacts());

            // which may cause some re-entrance in the build() method and can
            // actually cause deadlocks.  In order to workaround the problem,
            // we do a first pass by reading all rawModels in order.
            List<ProjectBuildingResult> results = new ArrayList<>();
            boolean failure = false;
            for (InterimResult r : interimResults) {

          <description>
            The relative path of the parent {@code pom.xml} file within the checkout.
            If not specified, it defaults to {@code ../pom.xml}.
            Maven looks for the parent POM first in this location on
            the filesystem, then the local repository, and lastly in the remote repo.
            {@code relativePath} allows you to select a different location,

    /**
     * Compares two model versions.
     *
     * @param first the first version.
     * @param second the second version.
     * @return negative if the first version is newer than the second version, zero if they are the same or positive if
     * the second version is the newer.
     */
    private static int compareModelVersions(String first, String second) {

import org.eclipse.aether.util.version.GenericVersionScheme;
import org.eclipse.aether.version.VersionScheme;

/**
 * A simple memorizing {@link Supplier} of {@link RepositorySystem} instance, that on first call
 * supplies lazily constructed instance, and on each subsequent call same instance. Hence, this instance should be
 * thrown away immediately once repository system was created and there is no need for more instances. If new

        assertSame(mirrorC, mirrorSelector.getMirror(getRepo("c", "http://c.c"), mirrors));
    }

    @Test
    void testMirrorStopOnFirstMatch() {
        // exact matches win first
        Mirror mirrorA2 = newMirror("a2", "a,b", "http://a2");
        Mirror mirrorA = newMirror("a", "a", "http://a");
        // make sure repeated entries are skipped

 * is meant for exclusive consumption by the model builder and is opaque to the cache implementation. The cache key is
 * formed by a combination of group id, artifact id, version and tag. The first three components generally refer to the
 * identity of a model. The tag allows for further classification of the associated data on the sole discretion of the
 * model builder.
 *
 */
public interface ModelCache {