this.id = lifecycle.id();
        this.phases = registry.computePhases(lifecycle);
        this.defaultPhases = getDefaultPhases(lifecycle);
    }

    // <lifecycle>
    //   <id>clean</id>
    //   <phases>
    //     <phase>pre-clean</phase>
    //     <phase>clean</phase>
    //     <phase>post-clean</phase>
    //   </phases>
    //   <default-phases>

        return phases();
    }

    /**
     * Stream of phases containing all child phases recursively.
     *
     * @return a stream of all phases in this lifecycle, including nested phases
     */
    default Stream<Phase> allPhases() {
        return phases().stream().flatMap(Phase::allPhases);
    }

    /**
     * Collection of aliases for this lifecycle.

     */
    public java.util.List<Phase> getPhases() {
        if (this.phases == null) {
            this.phases = new java.util.ArrayList<Phase>();
        }

        return this.phases;
    } // -- java.util.List<Phase> getPhases()

    /**
     * Method removePhase.
     *
     * @param phase a phase object.
     */
    public void removePhase(Phase phase) {
        getPhases().remove(phase);

     * the phase. Any {@link #AFTER} phases will still be executed.
     */
    AT(""),
    /**
     * Guaranteed execution dynamic phases on completion of the static phase. All {@code #AFTER} dynamic phases will
     * be executed provided at least one {@link #BEFORE} or {@link #AT} dynamic phase has started execution.
     */
    AFTER("after:");

                    }

                    @Override
                    public List<Phase> phases() {
                        return Collections.emptyList();
                    }

                    @Override
                    public Stream<Phase> allPhases() {
                        return Stream.concat(Stream.of(this), phases().stream().flatMap(Phase::allPhases));
                    }
                })

        if (lifecyclePhases.isEmpty()) {
            return Collections.emptyMap();
        }

        Map<String, String> phases = new LinkedHashMap<>();
        for (Map.Entry<String, LifecyclePhase> e : lifecyclePhases.entrySet()) {
            phases.put(e.getKey(), e.getValue().toString());
        }
        return phases;
    }

    }

    static Lifecycle.Phase phase(String name, Lifecycle.Link link1, Lifecycle.Link link2, Lifecycle.Phase... phases) {
        return new DefaultPhase(name, Collections.emptyList(), asList(link1, link2), asList(phases));
    }

    static Lifecycle.Phase phase(
            String name, Lifecycle.Link link1, Lifecycle.Link link2, Lifecycle.Link link3, Lifecycle.Phase... phases) {

        return phases;
    }

    @Deprecated
    public void setPhases(Map<String, String> phases) {
        Map<String, LifecyclePhase> lphases = new LinkedHashMap<>();
        for (Map.Entry<String, String> e : phases.entrySet()) {
            lphases.put(e.getKey(), new LifecyclePhase(e.getValue()));
        }
        setLifecyclePhases(lphases);
    }

We have a lifecycle mapping for the packaging of *jar* below. You see that for this packaging we have a *default* lifecycle and a list of phases where each phase is a comma separated list of goals to run and they are in the form groupId:artifactId:version.

<configuration>
  <lifecycles>
    <lifecycle>
      <id>default</id>
      <phases>
        <process-resources>org.apache.maven.plugins:maven-resources-plugin:resources</process-resources>

                    Map<String, LifecyclePhase> phases = getLifecyclePhases(lifecycleId);
                    if (phases != null) {
                        Lifecycle lifecycle = new Lifecycle();

                        lifecycle.setId(lifecycleId);
                        lifecycle.setLifecyclePhases(phases);

                        lifecycleMap.put(lifecycleId, lifecycle);
                    }