* @return The execution properties, never {@code null}.
     */
    Map<String, String> getSystemProperties();

    /**
     * Gets the user properties to use for interpolation and profile activation. The user properties have been
     * configured directly by the user on his discretion, e.g. via the {@code -Dkey=value} parameter on the command
     * line.
     *
     * @return The user properties, never {@code null}.
     */

                    cycle.removeLast();
                    stateMap.put(v, DfsState.VISITED);
                } else if (state == DfsState.VISITING) {
                    // we are already visiting this vertex, this mean we have a cycle
                    int pos = cycle.lastIndexOf(v);
                    List<String> ret = cycle.subList(pos, cycle.size());
                    ret.add(v);
                    return ret;
                }

            boolean reverseValue = false;
            if (propValue.startsWith("!")) {
                reverseValue = true;
                propValue = propValue.substring(1);
            }

            // we have a value, so it has to match the system value...
            return reverseValue != propValue.equals(sysValue);
        } else {
            return reverseName != (sysValue != null && !sysValue.isEmpty());
        }
    }

    private boolean includesDependencies;

    private String language;

    @Deprecated
    private boolean addedToClasspath;

    /**
     * Default ctor for Plexus compatibility, as many plugins have artifact handlers declared in legacy Plexus XML.
     * Do not use directly!
     *
     * @deprecated This ctor is present only for Plexus XML defined component compatibility, do not use it.
     */
    @Deprecated

                }
                cycle.removeLast();
                stateMap.put(v, DfsState.VISITED);
            } else if (state == DfsState.VISITING) {
                // we are already visiting this vertex, this mean we have a cycle
                int pos = cycle.lastIndexOf(v.label);
                List<String> ret = cycle.subList(pos, cycle.size());
                ret.add(v.label);
                return ret;
            }
        }

         * unique within a single POM. Upon multiple declarations, 2.x just kept the last one but retained the order of
         * the first occurrence. So when we're in lenient/compat mode, we have to deal with such broken POMs and mimic
         * the way 2.x works. When we're in strict mode, the removal of duplicates just saves other merging steps from
         * aftereffects and bogus error messages.
         */

        lifecycleStarter.execute(session);
    }

    // These methods deal with construction intact Plugin object that look like they come from a standard
    // <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.

        // ensure canonical order of standard lifecycles
        return lifecyclesMap.values().stream()
                .peek(l -> Objects.requireNonNull(l.getId(), "A lifecycle must have an id."))
                .sorted(Comparator.comparing(Lifecycle::getId, comparator))
                .collect(Collectors.toList());
    }

    private Map<String, Lifecycle> lookupLifecycles() {

    }

    public static Artifact copyArtifact(Artifact artifact) {
        VersionRange range = artifact.getVersionRange();

        // For some reason with the introduction of MNG-1577 we have the case in Yoko where a depMan section has
        // something like the following:
        //
        // <dependencyManagement>
        //     <dependencies>
        //         <!--  Yoko modules -->

     * method "filters" out in WHICH artifact are we interested in, but it intentionally neglects extension as
     * ArtifactDescriptorReader modifies extension to "pom" during collect. So all we have to rely on is GAV only.
     */
    static boolean isInScope(Artifact artifact, Artifact nodeArtifact) {
        return Objects.equals(artifact.getGroupId(), nodeArtifact.getGroupId())