<executions>
      <execution>
        <goals>
          <goal>process</goal>
        </goals>
      </execution>
    </executions>
  </plugin>
  .
  .
  .
</plugins>

import org.apache.maven.api.di.Named;
import org.apache.maven.api.di.Singleton;
import org.apache.maven.cling.invoker.mvnup.Goal;
import org.apache.maven.cling.invoker.mvnup.UpgradeContext;

/**
 * The "help" goal implementation.
 */
@Named("help")
@Singleton
public class Help implements Goal {

    @Override
    public int execute(UpgradeContext context) throws Exception {

 */
public class DuplicateMojoDescriptorException extends InvalidPluginDescriptorException {

    public DuplicateMojoDescriptorException(
            String goalPrefix, String goal, String existingImplementation, String newImplementation) {
        super("Goal: " + goal + " already exists in the plugin descriptor for prefix: " + goalPrefix
                + System.lineSeparator() + "Existing implementation is: " + existingImplementation

initialize them, you must run:

    git submodule init
    git submodule update

TODO
----

 * Add maven goal to avoid manual call to git submodule init.
 * Make hpack-test-case update itself from git, and run new tests.
 * Add maven goal to generate stories and a pull request to hpack-test-case
   to have others validate our output.

        <executions>
          <execution>
            <id>test</id>

            <!--  The key to this test... -->
            <inherited>false</inherited>

            <goals>
              <goal>compile</goal>
            </goals>
            <phase>install</phase>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>

          </params>
        </configuration>
        <executions>
          <execution>
            <id>velocity</id>
            <goals>
              <goal>velocity</goal>
            </goals>
            <phase>generate-sources</phase>
            <configuration>
              <templates>
                <template>merger.vm</template>

        plugin.setGroupId("org.apache.maven.plugins");
        plugin.setArtifactId(artifactId);

        for (String goal : goals) {
            PluginExecution pluginExecution = new PluginExecution();
            pluginExecution.setId("default-" + goal);
            pluginExecution.addGoal(goal);
            plugin.addExecution(pluginExecution);
        }

        return plugin;
    }

    @Override

            }
            if (isGoalSpecification(task)) {
                // "pluginPrefix[:version]:goal" or "groupId:artifactId[:version]:goal"

                lifecyclePluginResolver.resolveMissingPluginVersions(session.getTopLevelProject(), session);

                MojoDescriptor mojoDescriptor =

import java.io.IOException;

import org.apache.maven.api.services.MessageBuilderFactory;
import org.apache.maven.cling.invoker.mvnenc.Goal;
import org.codehaus.plexus.components.secdispatcher.SecDispatcher;

/**
 * The support class for goal implementations.
 */
public abstract class GoalSupport implements Goal {
    protected final MessageBuilderFactory messageBuilderFactory;
    protected final SecDispatcher secDispatcher;

                    for (String goal : execution.getGoals()) {
                        MojoDescriptor forkedMojoDescriptor;

                        if (goal.indexOf(':') < 0) {
                            forkedMojoDescriptor = pluginDescriptor.getMojo(goal);
                            if (forkedMojoDescriptor == null) {
                                throw new MojoNotFoundException(goal, pluginDescriptor);