+ " <plugin-group-id>:<plugin-artifact-id>[:<plugin-version>]:<goal>."
                        + " Available lifecycle phases are: " + defaultLifeCycles.getLifecyclePhaseList() + ".");
            }

            int degreeOfConcurrency = session.getRequest().getDegreeOfConcurrency();
            if (degreeOfConcurrency > 1) {

These particular phases in a plugin’s lifecycle can probably be generalized to all plugins so could be something implemented in all plugins. Here we could have the descriptor either point to methods for each of these phases to execute or we could create a lifecycle in Plexus for these phases.

For a particular application plugin there will be a declarative descriptor for that plugin type.

import org.apache.maven.plugin.descriptor.MojoDescriptor;
import org.apache.maven.project.MavenProject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * <p>
 * Logs debug output from the various lifecycle phases.
 * </p>
 * <strong>NOTE:</strong> This class is not part of any public api and can be changed or deleted without prior notice.
 *
 * @since 3.0
 */
@Named
@Singleton
public class LifecycleDebugLogger {

                        + " <plugin-group-id>:<plugin-artifact-id>[:<plugin-version>]:<goal>."
                        + " Available lifecycle phases are: " + defaultLifeCycles.getLifecyclePhaseList() + ".");
            }

            if (logger.isDebugEnabled()) {
                lifecycleDebugLogger.debugReactorPlan(projectBuilds);
            }

          <version>1.0.0+</version>
          <type>String</type>
          <description>The ID of this lifecycle, for identification in the mojo descriptor.</description>
        </field>
        <field>
          <name>phases</name>
          <version>1.0.0+</version>
          <description>The phase mappings for this lifecycle.</description>
          <association>
            <type>Phase</type>
            <multiplicity>*</multiplicity>

import org.apache.maven.plugin.MojoExecution;
import org.apache.maven.project.MavenProject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * <p>
 * Logs debug output from the various lifecycle phases.
 * </p>
 * <strong>NOTE:</strong> This class is not part of any public api and can be changed or deleted without prior notice.
 *
 * @since 3.0
 */
@Named
public class BuildPlanLogger {

     1. plugin goal execution in a child is usually simply appended (at end): you can't try to insert in the middle of pre-existing inherited executions,

     2. append happens at plugin level first, then goal level, independently from phases.
        This means for example that adding pluginA:goal2 to pre-existing (pluginA:goal1, pluginB:goal) will lead to (pluginA:goal1, pluginA:goal2, pluginB:goal)

        aliases.putAll(step.aliases);
    }

    private Map<String, BuildStep> merge(Map<String, BuildStep> org, Map<String, BuildStep> add) {
        // all new phases should be added after the existing ones
        List<BuildStep> lasts =
                org.values().stream().filter(b -> b.successors.isEmpty()).toList();
        List<BuildStep> firsts =

            associated with a Maven project can lack a file. As such, this annotation is meant for Mojos that only
            want to analyze the set of transitive dependencies, in particular during early lifecycle phases where
            full dependency resolution might fail due to projects which haven't been built yet.
          </description>
        </field>
        <field>
          <name>dependencyCollection</name>

      listeners.get(i).dispatch();
    }
  }

  /**
   * A special purpose queue/executor that dispatches listener events serially on a configured
   * executor. Each event can be added and dispatched as separate phases.
   *
   * <p>This class is very similar to {@link SequentialExecutor} with the exception that events can
   * be added without necessarily executing immediately.
   */