@Override
        protected ActivationFile.Builder transformActivationFile_Exists(
                Supplier<? extends ActivationFile.Builder> creator,
                ActivationFile.Builder builder,
                ActivationFile target) {
            stk.push(nextFrame("exists"));
            try {
                return super.transformActivationFile_Exists(creator, builder, target);
            } finally {
                stk.pop();

     */
    @Nonnull
    Optional<Path> getArtifactPath(@Nonnull Artifact artifact);

    /**
     * Gets the relative path for a locally installed artifact. Note that the artifact need not actually exist yet at
     * the returned location, the path merely indicates where the artifact would eventually be stored.
     * <p>
     * Shortcut for {@code getService(LocalArtifactManager.class).getPathForLocalArtitact(...)}.
     *

      <version>1.0.0+</version>
      <description>
        This is the file specification used to activate a profile. The missing value will be the location
        of a file that needs to exist, and if it doesn't the profile must run.  On the other hand exists will test
        for the existence of the file and if it is there will run the profile.
      </description>
      <fields>
        <field>
          <name>missing</name>

                    syncContext.acquire(null, Collections.singleton(metadata));

                    if (metadata.getPath() != null && Files.exists(metadata.getPath())) {
                        try (InputStream in = Files.newInputStream(metadata.getPath())) {
                            versioning =

            //                        }
            //                    );

            List<MetadataGraphEdge> exits = graph.getExcidentEdges(node);

            if (exits != null && exits.size() > 0) {
                MetadataGraphEdge[] sortedExits = exits.toArray(new MetadataGraphEdge[0]);
                Arrays.sort(sortedExits, (e1, e2) -> {
                    if (e1.getDepth() == e2.getDepth()) {

              echo "TEMP_MAVEN_BIN_DIR=$maven_bin_dir" >> $GITHUB_ENV
            else
              echo "$maven_bin_dir does not exist."
              exit 1;
            fi
          else
            echo "${{ env.TAR_BALL }} does not exist."
            exit 1;
          fi
        env:
          TAR_BALL: apache-maven/target/apache-maven-bin.tar.gz

      - name: Clean with Maven
        run: mvn clean

    public MetadataBridge(ArtifactMetadata metadata) {
        this.metadata = metadata;
    }

    public void merge(File current, File result) throws RepositoryException {
        try {
            if (current.exists()) {
                Files.createDirectories(result.toPath().getParent());
                Files.copy(current.toPath(), result.toPath());
            }
            ArtifactRepository localRepo = new MetadataRepository(result);

                unresolvedOptionalSelectors.add(selector);
            }
        }

        if (!unresolvedOptionalSelectors.isEmpty()) {
            LOGGER.info("The requested optional projects {} do not exist.", unresolvedOptionalSelectors);
        }

        return resolvedOptionalProjects;
    }

    private List<MavenProject> getChildProjects(MavenProject parent, MavenExecutionRequest request) {

      echo "JAVA_HOME is set to \"$JAVA_HOME\", but \"\$JAVA_HOME/bin/java\" does not exist." >&2
      exit 1
    fi
  fi
else
  JAVACMD="`\\unset -f command; \\command -v java`"

  if [ ! -x "$JAVACMD" ] ; then
    echo "The java(1) command does not exist in PATH nor is JAVA_HOME set, so Apache Maven cannot be started." >&2
    exit 1
  fi
fi

# traverses directory structure from process work directory to filesystem root

import static java.util.stream.Collectors.toSet;

/**
 * Container for storing the request from the user to activate or de-activate certain profiles and optionally fail the
 * build if those profiles do not exist.
 */
public class ProfileActivation {
    private final Map<String, ActivationSettings> activations = new HashMap<>();

    /**
     * Mimics the pre-Maven 4 "active profiles" list.