*
     * @return the severity level of this problem, never {@code null}
     */
    @Nonnull
    Severity getSeverity();

    /**
     * The different severity levels for a problem, in decreasing order.
     *
     * @since 4.0.0
     */
    @Experimental
    enum Severity {
        FATAL, //
        ERROR, //
        WARNING //
    }

         * NOTE: This is primarily to keep backward-compat with Maven 2.x which did not validate that dependencies are
         * 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

// TODO lifecycles being executed
// TODO what runs in each phase
// TODO plugins that need downloading
// TODO project dependencies that need downloading
// TODO unfortunately the plugins need to be downloaded in order to get the plugin.xml file. need to externalize this
//      from the plugin archive.
// TODO this will be the class that people get in IDEs to modify

/**
 * MavenExecutionPlan
 */

                return rx - lx;
            } else {
                return lx - rx;
            }
        };

        Map<String, Lifecycle> lifecyclesMap = lookupLifecycles();

        // ensure canonical order of standard lifecycles
        return lifecyclesMap.values().stream()
                .peek(l -> Objects.requireNonNull(l.getId(), "A lifecycle must have an id."))

/**
 * Evaluator for plugin parameters expressions. Content surrounded by <code>${</code> and <code>}</code> is evaluated.
 * Recognized values are:
 * <table border="1">
 * <caption>Expression matrix</caption>
 * <tr><th>expression</th>                     <th></th>               <th>evaluation result</th></tr>

                acquiredAggregatorLock = null;
                acquiredProjectLock = null;
            }
        }

        @Override
        public void close() {
            // release the lock in the reverse order of the acquisition
            if (acquiredProjectLock != null) {
                acquiredProjectLock.unlock();
            }
            if (acquiredAggregatorLock != null) {

                prefixlessObjectBasedValueSource =
                        new ProblemDetectingValueSource(prefixlessObjectBasedValueSource, "", PREFIX_PROJECT, problems);
            }
        }

        // NOTE: Order counts here!
        List<ValueSource> valueSources = new ArrayList<>(9);

        if (projectDir != null) {
            ValueSource basedirValueSource = new PrefixedValueSourceWrapper(

 * all components from this class, and the upfront construction taken care of entirely by the {@link ProjectBuilder}.
 * 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 {

            resource to allow Maven to merge changes to this resource that take
            place during the execution of a plugin. This field must be managed
            by the generated parser and formatter classes in order to allow it
            to survive model interpolation.
          </description>
          <type>String</type>
        </field>
      </fields>
      <codeSegments>
        <codeSegment>

    @Override
    String id();

    /**
     * Collection of phases for this lifecycle
     */
    Collection<Phase> phases();

    /**
     * Pre-ordered list of phases.
     * If not provided, a default order will be computed.
     */
    default Optional<List<String>> orderedPhases() {
        return Optional.empty();
    }

    /**
     * A phase in the lifecycle.
     */
    interface Phase {