* Whether module hierarchy was detected. If false, then package hierarchy is assumed.
     * In a package hierarchy, the {@linkplain #descriptors} map has either zero or one entry.
     * In a module hierarchy, the descriptors map may have an arbitrary number of entries,
     * including one (so the map size cannot be used as a criterion).
     *
     * @see #isModuleHierarchy()
     */
    private final boolean isModuleHierarchy;

    /**

        }

        // After the collection we will have the artifact object in the result but they will not be resolved yet.
        result = artifactCollector.collect(
                artifacts, rootArtifact, managedVersions, collectionRequest, source, collectionFilter, listeners, null);

        // We have metadata retrieval problems, or there are cycles that have been detected

import static org.junit.jupiter.api.Assertions.assertTrue;

// It would be cool if there was a hook that I could use to set up a test environment.
// I want to set up a local/remote repositories for testing but I don't want to have
// to change them when I change the layout of the repositories. So I want to generate
// the structure I want to test by using the artifact handler manager which dictates
// the layout used for a particular artifact type.

/**

     */
    @Nonnull
    Collection<Profile> getProfiles();

    /**
     * List of profile ids that have been explicitly activated by the user.
     */
    @Nonnull
    List<String> getActiveProfileIds();

    /**
     * List of profile ids that have been explicitly deactivated by the user.
     */
    @Nonnull
    List<String> getInactiveProfileIds();

    /**

    private final Properties executionProperties;

    private ThreadLocal<MavenProject> currentProject = new ThreadLocal<>();

    /**
     * These projects have already been topologically sorted in the {@link org.apache.maven.Maven} component before
     * being passed into the session. This is also the potentially constrained set of projects by using --projects
     * on the command line.

     *         <p>
     *         The restrictions of the returned version range will be an intersection of the restrictions
     *         of this version range and the specified version range if both version ranges have
     *         restrictions. Otherwise, the restrictions on the returned range will be empty.
     *         </p>
     *         <p>

                settingsMerger.merge(user, settingsMerger.merge(project, global, false, null), false, null);

        // If no repository is defined in the user/global settings,
        // it means that we have "old" settings (as those are new in 4.0)
        // so add central to the computed settings for backward compatibility.
        if (effective.getRepositories().isEmpty()

        ArtifactSpec b = a.addDependency("b", "1.0");
        b.addDependency("a", "1.0");
        assertThrows(
                CyclicDependencyException.class,
                () -> collect(a),
                "Should have failed on cyclic dependency not involving project");
    }

    @Test
    @Disabled("works, but we don't fail on cycles presently")
    void testCircularDependencyIncludingCurrentProject()

  operations to fail, then trying to help users decipher the error messages they
  get as a result.

* Implications for Resolution

** Dependency Resolution

  This one is obvious...we only have access to the repositories using
  the file:// protocol and living on a truly local filesystem when
  offline.

** Plugin Resolution

  This is similar to dependency resolution. Plugin repositories not

        } catch (MavenExecutionException e) {
            return addExceptionToResult(result, e);
        }

        //
        // The projects need to be topologically after the participants have run their afterProjectsRead(session)
        // because the participant is free to change the dependencies of a project which can potentially change the