}

        /**
         * Returns the option followed by a string representation of the given path elements.
         * The path elements are separated by an option-specific or platform-specific separator.
         * If the given {@code paths} argument contains no element, then this method returns an empty string.
         *
         * @param paths the path to format as a string

     * Returns the project artifacts as immutable list. Elements are the project POM artifact and the artifact
     * produced by this project build, if applicable. Hence, the returned list may have one or two elements
     * (never less than 1, never more than 2), depending on project packaging.
     * <p>
     * The list's first element is ALWAYS the project POM artifact. Presence of second element in the list depends
     * solely on the project packaging.

        dependencies = new LinkedHashMap<>(count + count / 3);
    }

    /**
     * Adds the given path element to the specified type of path.
     *
     * @param type the type of path (class-path, module-path, …)
     * @param path the path element to add
     */
    private void addPathElement(PathType type, Path path) {

     * The head of returned list is result of {@link Project#getArtifacts()} method, so same applies here: the list can have
     * minimum of one element. The maximum number of elements is in turn dependent on build configuration and lifecycle
     * phase when this method was invoked (i.e. is javadoc jar built and attached, is sources jar built attached, are
     * all the artifact signed, etc.).

import org.apache.maven.api.annotations.Nonnull;

/**
 * Information about the modules contained in a path element.
 * The path element may be a JAR file or a directory. Directories may use either package hierarchy
 * or module hierarchy, but not module source hierarchy. The latter is excluded because this class
 * is for path elements of compiled codes.
 */
class PathModularization {
    /**

                for (Plugin element : src) {
                    Object key = getPluginKey().apply(element);
                    managedPlugins.put(key, element);
                }

                List<Plugin> newPlugins = new ArrayList<>();
                for (Plugin element : target.getPlugins()) {
                    Object key = getPluginKey().apply(element);

                for (Plugin element : tgt) {
                    Object key = getPluginKey().apply(element);
                    Plugin existing = master.get(key);
                    if (existing != null) {
                        element = mergePlugin(element, existing, sourceDominant, context);

                        master.put(key, element);

                        if (!pending.isEmpty()) {

            }

            for (Repository element : dominant) {
                Object key = getRepositoryKey().apply(element);
                merged.put(key, element);
            }

            for (Repository element : recessive) {
                Object key = getRepositoryKey().apply(element);
                if (!merged.containsKey(key)) {
                    merged.put(key, element);
                }
            }

                for (Plugin element : tgt) {
                    Object key = getPluginKey().apply(element);
                    merged.put(key, element);
                }

                Map<Object, Plugin> added = new LinkedHashMap<>();

                for (Plugin element : src) {
                    Object key = getPluginKey().apply(element);
                    Plugin existing = merged.get(key);

  <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/>

  <repositories>
    <repository>
      <id>equal-repo-id</id>
      <url>file:///${basedir}/null</url>
      <snapshots/>
      <releases/>