// 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
 */
public class MavenExecutionPlan implements Iterable<ExecutionPlanItem> {

    /*

        is the location of a file that needs to exist, and if it doesn't, the profile will be
        activated. On the other hand, {@code exists} will test for the existence of the file and if it is
        there, the profile will be activated.
        <p>Variable interpolation for these file specifications is limited to {@code ${project.basedir}},

    /**
     * Aggregating mojo executions (possibly) modify all MavenProjects, including those that are currently in use
     * by concurrently running mojo executions. To prevent race conditions, an aggregating execution will block
     * all other executions until finished.
     * We also lock on a given project to forbid a forked lifecycle to be executed concurrently with the project.

 */
@Experimental
public interface TypeRegistry extends ExtensibleEnumRegistry<Type> {

    /**
     * Obtain the {@link Type} from the specified {@code id}.
     * If no type is known for {@code id}, the registry will
     * create a custom {@code Type} for it.
     *
     * @param id the id of the type to retrieve
     * @return the type
     */
    @Nonnull
    @Override
    default Type require(@Nonnull String id) {

import org.apache.maven.api.annotations.Nullable;

import static org.apache.maven.api.services.BaseRequest.nonNull;

/**
 * A Source specific to load POMs.  The {@link #resolve(ModelLocator, String)} method
 * will be used to find POMs for children modules.
 *
 * @since 4.0.0
 */
public interface ModelSource extends Source {

    interface ModelLocator {
        /**

            // even before the arguments from the command line are parsed.  Any exception
            // that would happen here should cause the build to fail at a later stage
            // (when actually parsing the POM) and will lead to a better exception being
            // displayed to the user, so just bail out and return false.
        }
        return false;
    }

    /**
     * Retrieve of compute the data associated with the specified key.
     *
     * @param key the key for which to retrieve the session data, must not be {@code null}
     * @param supplier the supplier will compute the new value
     * @return the session data associated with the key
     */
    @Nullable
    <T> T computeIfAbsent(@Nonnull Key<T> key, @Nonnull Supplier<T> supplier);

    /**

            //
            // mvn remote-resources:process
            //
            // From the metadata stored on the server which has been created as part of a standard
            // Maven plugin deployment we will find the right PluginDescriptor from the remote
            // repository.

            plugin = findPluginForPrefix(prefix, session);
        }

        int executionIdx = goal.indexOf('@');

     * coordinates.
     *
     * @param artifact the artifact to add or replace.
     * @deprecated Please use {@link MavenProjectHelper}
     * @throws DuplicateArtifactAttachmentException will never happen but leave it for backward compatibility
     */
    public void addAttachedArtifact(Artifact artifact) throws DuplicateArtifactAttachmentException {
        // if already there we remove it and add again

                RepositorySystemSession repositorySystemSession =
                        executionEvent.getSession().getRepositorySession();
                validationReportLevel(repositorySystemSession); // this will parse and store it in session.data
                validationPluginExcludes(repositorySystemSession);
            } else if (executionEvent.getType() == ExecutionEvent.Type.SessionEnded) {