newComparable("0-x");
        newComparable("0.rc");
        newComparable("0-1");

        ComparableVersion version = new ComparableVersion("0.x");
        assertEquals("x", version.getCanonical());
        ComparableVersion version2 = new ComparableVersion("0.2");
        assertEquals("0.2", version2.getCanonical());
    }

    /**
     * Test <a href="https://issues.apache.org/jira/browse/MNG-5568">MNG-5568</a> edge case

                                        if (versions == null) {
                                            versions = source.retrieveAvailableVersions(metadataRequest);
                                            artifact.setAvailableVersions(versions);
                                        }

                                        Collections.sort(versions);

     *         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>
     *         The recommended version of the returned version range will be the recommended version of
     *         this version range, provided that ranges falls within the intersected restrictions. If

                .map(MavenProject::getVersion)
                .collect(Collectors.collectingAndThen(Collectors.toList(), Collections::unmodifiableList));
        if (!versions.isEmpty()) {
            return versions;
        }
        return getAllProjects()
                .getOrDefault(artifact.getGroupId(), Collections.emptyMap())
                .getOrDefault(artifact.getArtifactId(), Collections.emptyMap())
                .values()

            }

            @Override
            public List<ArtifactVersion> retrieveAvailableVersionsFromDeploymentRepository(
                    Artifact artifact, ArtifactRepository localRepository, ArtifactRepository remoteRepository) {
                throw new UnsupportedOperationException("Cannot get available versions in this test case");
            }

versions of the General Public License from time to time. Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns.

Each version is given a distinguishing version number. If the Program
specifies a version number of this License which applies to it and "any
later version", you have the option of following the terms and

     * construct graph from a "dirty" tree
     *
     * @param tree "dirty" tree root
     * @param versionedVertices true if graph nodes should be versioned (different versions -> different nodes)
     * @param scopedVertices true if graph nodes should be versioned and scoped
     * (different versions and/or scopes -> different nodes)
     *
     */

    private ArtifactSpec createArtifactSpec(String id, String version) throws InvalidVersionSpecificationException {
        return createArtifactSpec(id, version, Artifact.SCOPE_COMPILE);
    }

    private ArtifactSpec createArtifactSpec(String id, String version, boolean optional)
            throws InvalidVersionSpecificationException {
        return createArtifactSpec(id, version, Artifact.SCOPE_COMPILE, null, optional);
    }

            if (versionRangeResult.getHighestVersion() == null) {
                throw new UnresolvableModelException(
                        String.format(
                                "No versions matched the requested parent version range '%s'", parent.getVersion()),
                        parent.getGroupId(),
                        parent.getArtifactId(),
                        parent.getVersion());
            }

     * In this case though, the result contains simply the (parsed) input version, regardless of the
     * repositories and their contents.
     *
     * @param artifact the artifact for which to resolve the versions
     * @return a list of resolved {@code Version}s.
     * @throws org.apache.maven.api.services.VersionRangeResolverException if the resolution failed