/**
     * Gets the current project (if any).
     *
     * @return the current project or {@code empty()} if not applicable
     */
    @Nonnull
    Optional<Project> getProject();

    /**
     * Gets the current mojo execution (if any).
     *
     * @return the current mojo execution or {@code empty()} if not applicable
     */
    @Nonnull
    Optional<MojoExecution> getMojoExecution();

    /**

        assertNotNull(list, "No dependencies");
        assertTrue(!list.isEmpty(), "Empty dependency list");

        Map<?, ?> map = projectToClone.getManagedVersionMap();
        assertNotNull(map, "No ManagedVersionMap");
        assertTrue(!map.isEmpty(), "ManagedVersionMap is empty");

        MavenProject clonedProject = projectToClone.clone();

     *
     * @param settings The settings' string representation, may be empty or {@code null}.
     */
    public StringSettingsSource(CharSequence settings) {
        this(settings, null);
    }

    /**
     * Creates a new settings source backed by the specified string.
     *
     * @param settings The settings' string representation, may be empty or {@code null}.

 *
 * @since 3.0.2
 */
public interface RuntimeInformation {

    /**
     * Retrieves the current Maven version, for example "3.0.2".
     *
     * @return The current Maven version or an empty string if unknown, never {@code null}.
     */
    String getMavenVersion();

    /**
     * Checks whether the current Maven runtime matches the specified version range. A version range can either use the

     * from the collection obtained by {@link #getModelIds()}. As a special case, an empty string can be used as the
     * identifier for the super POM.
     *
     * @param modelId The identifier of the model whose active profiles should be retrieved, must not be {@code null}.
     * @return The active profiles of the model or an empty list if none or {@code null} if the specified model id does
     *         not refer to a known model.

     * from the collection obtained by {@link #getModelIds()}. As a special case, an empty string can be used as the
     * identifier for the super POM.
     *
     * @param modelId The identifier of the model whose active profiles should be retrieved, must not be {@code null}.
     * @return The active profiles of the model or an empty list if the specified model id does
     *         not refer to a known model or has no active profiles.

     *            empty.
     * @param pluginArtifactId The artifact id of the plugin whose configuration should be used, must not be
     *            {@code null} or empty.
     * @param pluginExecutionId The id of a plugin execution whose configuration should be used, may be {@code null} or
     *            empty to use the general plugin configuration.

     * is thrown so this information is merely meant to assist the user.
     *
     * @return the identifier of the project or an empty string if not known, never {@code null}
     */
    @Nonnull
    String getProjectId();

    /**
     * Gets the POM file from which the project was built.
     *
     * @return the optional POM file
     */

  <name>Maven Integration Test :: MNG-3979</name>
  <description>
    Test that during inheritance the merging/joining of subtrees with equal identifier doesn't crash if the parent
    POM has a non-empty element and the child POM has an empty element to join.
  </description>

  <properties>
    <prop0>test</prop0>
  </properties>

  <repositories>
    <repository>
      <id>equal-repo-id</id>

    }

    public static String key(String groupId, String artifactId, String version) {
        notBlank(groupId, "groupId can neither be null, empty nor blank");
        notBlank(artifactId, "artifactId can neither be null, empty nor blank");
        notBlank(version, "version can neither be null, empty nor blank");

        return groupId + ":" + artifactId + ":" + version;
    }

    private static void notBlank(String str, String message) {