class Graph {

    final Map<String, Set<String>> graph = new LinkedHashMap<>();

    synchronized void addEdge(String from, String to) throws CycleDetectedException {
        if (graph.computeIfAbsent(from, l -> new HashSet<>()).add(to)) {
            List<String> cycle = visitCycle(graph, Collections.singleton(to), new HashMap<>(), new LinkedList<>());
            if (cycle != null) {
                // remove edge which introduced cycle

    // <plugin/> block in a Maven POM. We have to do some wiggling to pull the sources of information
    // together and this really shows the problem of constructing a sensible default configuration but
    // it's all encapsulated here so it appears normalized to the POM builder.

    // We are going to take the project packaging and find all plugin in the default lifecycle and create

            // even before the arguments from the command line are parsed.  Any exception
            // that would happen here should cause the build to fail at a later stage
            // (when actually parsing the POM) and will lead to a better exception being
            // displayed to the user, so just bail out and return false.
        }
        return false;
    }

     * creator of the problem, the general expectation is that the hint provides sufficient information to the user to
     * track the problem back to its origin. A concrete example for such a source hint can be the file path or URL from
     * which the settings were read.
     *

 * There is still the issue of having to run the lifecycle in order to find all the compile source roots and resource
 * directories but I hope to take care of this during the Maven 4.0 release (jvz).
 * </p>
 */
public class MavenProject implements Cloneable {

    private static final Logger LOGGER = LoggerFactory.getLogger(MavenProject.class);

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *

    /**
     * Running Maven under JDK7 may cause connection issues because IPv6 is used by default.
     * <p>
     * e.g running mvn site:run will cause Jetty to fail.
     * </p>
     * <p>
     * The resolution is to add -Djava.net.preferIPv4Stack=true to the command line as documented in
     * http://cwiki.apache.org/confluence/display/MAVEN/ConnectException
     * </p>
     */
    @Test
    void testJdk7ipv6() {

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *

     * determinism, the environment variable names will be normalized to upper case on platforms with case-insensitive
     * variable lookup.
     *
     * @param props The properties to add the environment variables to, may be {@code null}.
     */
    public static void addEnvVars(Properties props) {
        if (props != null) {
            if (envVars == null) {

/**
 * Exception which occurs to indicate that the plugin cannot be initialized due
 * to some deeper problem with Plexus. Context information includes the groupId,
 * artifactId, and version for the plugin; at times, the goal name for which
 * execution failed; a message detailing the problem; the ClassRealm used to
 * look up the plugin; and the Plexus exception that caused this error.
 *
 *
 */