import java.util.ArrayList;
import java.util.Collection;

/**
 * This is the main graph data structure used by the RepositorySystem to present tree and graph objects.
 *
 *
 */
@Deprecated
public class MetadataGraph {
    /** all graph nodes */
    Collection<MetadataGraphNode> nodes;

    /** entry point for tree-like structures */
    MetadataGraphNode entry;

    public MetadataGraph(MetadataGraphNode entry) {

          <type>DOM</type> <!-- DOM for Maven 2.0.9/2.3.3 -->
          <description>
            Toolchain identification information, which will be matched against project requirements.
            &lt;p>Actual content structure is completely open: each toolchain type will define its own format and
            semantics.
            &lt;p>This is generally a properties format: {@code &lt;name&gt;value&lt;/name&gt;} with predefined

 <parent>
   <groupId></groupId>
   <artifactId></artifactId>
   <version></version>
 </parent>
</project>
+-----+

Extending the POM in the future

  In order to anticipate changes in the structure of the POM as new releases of
  maven occur, the maven inheritance model must be pinned against a particular
  modelVersion. This is required so that a change from modelVersion 4.0.0 to

      pre-calculated execution plan that stays the same during the execution.

      If deciding to add mutable state to this class, it should be at least considered to
      separate this into a separate mutable structure.

    */

    private final List<ExecutionPlanItem> planItem;

    private final Map<String, ExecutionPlanItem> lastMojoExecutionForAllPhases;

    final List<String> phasesInExecutionPlan;

identify which stub creates that specific piece of data.

The most important stubs are:
LifecycleExecutionPlanCalculatorStub
ProjectDependencyGraphStub

Since they define the primary structure of the project/build.

The stubs define three top-level targets that are defined in  LifecycleTaskSegmentCalculatorStub;
clean, aggr and install. "aggr" is an aggregating task while clean and install are lifecyclephases.

  if [ ! -x "$JAVACMD" ] ; then
    echo "The java(1) command does not exist in PATH nor is JAVA_HOME set, so Apache Maven cannot be started." >&2
    exit 1
  fi
fi

# traverses directory structure from process work directory to filesystem root
# first directory with .mvn subdirectory is considered project base directory
find_maven_basedir() {
(
  basedir=`find_file_argument_basedir "$@"`
  wdir="$basedir"

// I want to set up a local/remote repositories for testing but I don't want to have
// to change them when I change the layout of the repositories. So I want to generate
// the structure I want to test by using the artifact handler manager which dictates
// the layout used for a particular artifact type.

/**
 */
@Deprecated
class ArtifactResolverTest extends AbstractArtifactComponentTestCase {

       <name>theme</name>
       <value>classic</value>
     </parameter>
   </parameters>
  </plugin>
</plugins>
+-----+

Unified source directory

 Unified source directory structure that is analogous to the repository
 itself. This way locations of intermediary artifacts of a build would be
 in a known location. This would also help with developer setup i.e. getting

import static org.mockito.ArgumentMatchers.anyList;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.when;

class DefaultGraphBuilderTest {
    /*
    The multi-module structure in this project is displayed as follows:

    module-parent
    └─── module-independent     (without parent declaration)
         module-a
         module-b               (depends on module-a)
         module-c

            buffer.append(" instead of ").append(parent.getGroupId()).append(':');
            buffer.append(parent.getArtifactId()).append(", please verify your project structure");

            problems.setSource(childModel);
            problems.add(Severity.WARNING, ModelProblem.Version.BASE, buffer.toString(), parent.getLocation(""));
            return null;
        }