Entry<String, String> next;

                    {
                        advance();
                    }

                    private void advance() {
                        next = null;
                        while (iterator.hasNext()) {
                            Entry<Object, Object> e = iterator.next();
                            if (PropertiesAsMap.matches(e)) {

                    Entry<String, String> next;

                    {
                        advance();
                    }

                    private void advance() {
                        next = null;
                        while (iterator.hasNext()) {
                            Entry<Object, Object> e = iterator.next();
                            if (PropertiesAsMap.matches(e)) {

        return new Iterator<U>() {
            @Override
            public boolean hasNext() {
                return it.hasNext();
            }

            @Override
            public U next() {
                return mapper.apply(it.next());
            }
        };
    }

    @Override
    public int size() {
        return list.size();
    }

     */
    void add(Problem.Severity severity, String message, int line, int column, Exception cause);

    /**
     * The next messages will be bound to this source. When calling this method again, previous messages keep
     * their source, but the next messages will use the new source.
     *
     * @param source a source
     */
    void setSource(String source);

    /**
     *

                    // move on to next in r1
                    if (i1.hasNext()) {
                        res1 = i1.next();
                    } else {
                        done = true;
                    }
                }
            } else {
                // move on to next in r2
                if (i2.hasNext()) {
                    res2 = i2.next();
                } else {

     */
    boolean enter(@Nonnull Node node);

    /**
     * Ends the visit to the specified dependency node.
     *
     * @param node the dependency node to visit
     * @return <code>true</code> to visit the specified dependency node's next sibling, <code>false</code> to skip the
     *         specified dependency node's next siblings and proceed to its parent
     */

        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 (Object next : feedback) {
                            if (next instanceof Throwable) {
                                if (last == null) {
                                    logger.debug("", ((Throwable) next));
                                } else {
                                    logger.debug(String.valueOf(last), ((Throwable) next));
                                }

        return new Iterator<U>() {
            @Override
            public boolean hasNext() {
                return it.hasNext();
            }

            @Override
            public U next() {
                return mapper.apply(it.next());
            }
        };
    }

    @Override
    public int size() {
        return list.size();
    }

        if (r1.size() != r2.size()) {
            return false;
        }

        for (Iterator<ArtifactRepository> it1 = r1.iterator(), it2 = r2.iterator(); it1.hasNext(); ) {
            if (!repositoryEquals(it1.next(), it2.next())) {
                return false;
            }
        }

        return true;
    }

    /**
     * CacheRecord
     */
    public class CacheRecord {