for (Plugin plugin : plugins) {
                Object key = plugin.getKey();
                Plugin first = normalized.get(key);
                if (first != null) {
                    plugin = merger.mergePlugin(plugin, first);
                }
                normalized.put(key, plugin);
            }

            if (plugins.size() != normalized.size()) {

 * is typically also used for tests.
 */
class PathModularizationCache {
    /**
     * Module information for each JAR file or output directories.
     * Cached when first requested to avoid decoding the module descriptors multiple times.
     *
     * @see #getModuleInfo(Path)
     */
    private final Map<Path, PathModularization> moduleInfo;

    /**

        if (!projects.isEmpty()) {
            MavenProject first = projects.get(0);
            this.currentProject = ThreadLocal.withInitial(() -> first);
            this.topLevelProject = projects.stream()
                    .filter(project -> project.isExecutionRoot())
                    .findFirst()
                    .orElse(first);
        } else {
            this.currentProject = new ThreadLocal<>();

        printErrors(result);

        Iterator<Artifact> i = result.getArtifacts().iterator();
        assertEquals(n, i.next(), "n should be first");
        assertEquals(m, i.next(), "m should be second");

        // inverse order
        set = new LinkedHashSet<>();
        set.add(m);
        set.add(n);

        for (Lifecycle lifecycle : getLifeCycles()) {
            logger.debug("Lifecycle {}", lifecycle);

            for (String phase : lifecycle.getPhases()) {
                // The first definition wins.
                if (!phaseToLifecycleMap.containsKey(phase)) {
                    phaseToLifecycleMap.put(phase, lifecycle);
                } else if (logger.isWarnEnabled()) {

 * is meant for exclusive consumption by the model builder and is opaque to the cache implementation. The cache key is
 * formed by a combination of group id, artifact id, version and tag. The first three components generally refer to the
 * identity of a model. The tag allows for further classification of the associated data on the sole discretion of the
 * model builder.
 *
 */
public interface ModelCache {

    static {
        // Those two public constants are initialized here, as they need all the private constants
        // above to be initialized first, but the code style imposes the public constants to be
        // defined above the private ones...
        OS_FAMILY = getOsFamily();
        IS_WINDOWS = isFamily(FAMILY_WINDOWS);
    }

    private Os() {}

    /**
     * Gets the sequence of model identifiers that denote the lineage of models from which the effective model was
     * constructed. Model identifiers have the form {@code <groupId>:<artifactId>:<version>}. The first identifier from
     * the list denotes the model on which the model builder was originally invoked. The last identifier will always be
     * an empty string that by definition denotes the super POM.
     *

        }
        return buffer.toString();
    }

    private static void join(StringBuilder buffer, List<String> details, String separator) {
        boolean first = true;
        for (String detail : details) {
            if (first) {
                first = false;
            } else {
                buffer.append(separator);
            }
            buffer.append(detail);
        }
    }

-----------------------------------
You can download the release source from our [download page][maven-download].

Contributing
------------

If you are interested in the development of Maven, please consult the
documentation first and afterward you are welcome to join the developers
mailing list to ask questions or discuss new ideas/features/bugs etc.

Take a look into the [contribution guidelines](CONTRIBUTING.md).

License
-------