return null;
    }

    private static final long serialVersionUID = 0;
  }

  /**
   * Returns a view of the elements of {@code unfiltered} that satisfy a predicate. The returned
   * multiset is a live view of {@code unfiltered}; changes to one affect the other.
   *
   * <p>The resulting multiset's iterators, and those of its {@code entrySet()} and {@code

    if (comparator != null) { // can't use ? : because of javac bug 5080917
      return comparator;
    }
    return (Comparator<E>) Ordering.natural();
  }

  /**
   * Returns a live {@link Map} view whose keys are the contents of {@code set} and whose values are
   * computed on demand using {@code function}. To get an immutable <i>copy</i> instead, use {@link
   * #toMap(Iterable, Function)}.
   *

        return set1.contains(element) ^ set2.contains(element);
      }
    };
  }

  /**
   * Returns the elements of {@code unfiltered} that satisfy a predicate. The returned set is a live
   * view of {@code unfiltered}; changes to one affect the other.
   *
   * <p>The resulting set's iterator does not support {@code remove()}, but all other set methods

    public void clear() {
      multimap.clear();
    }
  }

  /**
   * Returns a multimap containing the mappings in {@code unfiltered} whose keys satisfy a
   * predicate. The returned multimap is a live view of {@code unfiltered}; changes to one affect
   * the other.
   *
   * <p>The resulting multimap's views have iterators that don't support {@code remove()}, but all

 */
@Experimental
public class LookupException extends MavenException {

    public LookupException(String message) {
        super(message);
    }

    /**
     * @param message the message to give
     * @param e the {@link Exception}
     */
    public LookupException(String message, Exception e) {
        super(message, e);
    }

    /**
     * @param e the {@link Exception}
     */

 * that the plugins/mojos can be used in arbitrary contexts. In particular, the mojos can be used for ordinary build
 * plugins as well as special purpose plugins like reports.
 *
 * @since 3.0
 */
@Named
@Singleton
public class DefaultMavenPluginManager implements MavenPluginManager {

    /**
     * <p>

    SessionData getData();

    /**
     * Returns immutable user properties to use for interpolation. The user properties have been configured directly
     * by the user, e.g. via the {@code -Dkey=value} parameter on the command line.
     *
     * @return the user properties, never {@code null}
     */
    @Nonnull
    Map<String, String> getUserProperties();

    /**

              "DelayedShutdownHook-for-" + service,
              new Runnable() {
                @Override
                public void run() {
                  try {
                    // We'd like to log progress and failures that may arise in the
                    // following code, but unfortunately the behavior of logging
                    // is undefined in shutdown hooks.

        ArtifactResolutionResult result = new ArtifactResolutionResult();

        // The root artifact may, or may not be resolved so we need to check before we attempt to resolve.
        // This is often an artifact like a POM that is taken from disk and we already have hold of the
        // file reference. But this may be a Maven Plugin that we need to resolve from a remote repository
        // as well as its dependencies.

            buffer.append(getSource());
        }
        if (getLineNumber() > 0) {
            if (!buffer.isEmpty()) {
                buffer.append(", ");
            }
            buffer.append("line ").append(getLineNumber());
        }
        if (getColumnNumber() > 0) {
            if (!buffer.isEmpty()) {
                buffer.append(", ");
            }