// default does nothing
    }

    public void projectSucceeded(ExecutionEvent event) {
        // default does nothing
    }

    public void projectFailed(ExecutionEvent event) {
        // default does nothing
    }

    public void forkStarted(ExecutionEvent event) {
        // default does nothing
    }

    public void forkSucceeded(ExecutionEvent event) {
        // default does nothing
    }

@GwtCompatible
public enum MapFeature implements Feature<Map> {
  /**
   * The map does not throw {@code NullPointerException} on calls such as {@code containsKey(null)},
   * {@code get(null)}, {@code keySet().contains(null)} or {@code remove(null)}.
   */
  ALLOWS_NULL_KEY_QUERIES,
  ALLOWS_NULL_KEYS(ALLOWS_NULL_KEY_QUERIES),
  /**
   * The map does not throw {@code NullPointerException} on calls such as {@code

   *
   * <p>Like {@link BufferedReader#readLine()}, this method considers a line to be a sequence of
   * text that is terminated by (but does not include) one of {@code \r\n}, {@code \r} or {@code
   * \n}. If the source's content does not end in a line termination sequence, it is treated as if
   * it does.
   *
   * <p>The caller is responsible for ensuring that the returned stream is closed. For example:
   *
   * <pre>{@code

 */
@Deprecated(since = "4.0.0")
public interface ModelLocator {

    /**
     * Locates the POM file within the specified project directory. In case the given project directory does not exist
     * or does not contain a POM file, the return value indicates the expected path to the POM file. Subdirectories of
     * the project directory will not be considered when locating the POM file. The return value will be an absolute

    @Override
    public boolean add(@ParametricNullness V element) {
      throw new IllegalArgumentException("Key does not satisfy predicate: " + key);
    }

    @Override
    public boolean addAll(Collection<? extends V> collection) {
      checkNotNull(collection);
      throw new IllegalArgumentException("Key does not satisfy predicate: " + key);
    }

    @Override
    protected Set<V> delegate() {

      echo "JAVA_HOME is set to \"$JAVA_HOME\", but \"\$JAVA_HOME/bin/java\" does not exist." >&2
      exit 1
    fi
  fi
else
  JAVACMD="`\\unset -f command; \\command -v java`"

  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

            userSettingsFile = resolveFile(userSettingsFile, workingDirectory);

            if (!userSettingsFile.isFile()) {
                throw new FileNotFoundException("The specified user settings file does not exist: " + userSettingsFile);
            }
        } else {
            userSettingsFile = DEFAULT_USER_SETTINGS_FILE;
        }

        File projectSettingsFile;

    return AllEqualOrdering.INSTANCE;
  }

  /**
   * Returns an ordering that compares objects by the natural ordering of their string
   * representations as returned by {@code toString()}. It does not support null values.
   *
   * <p>The comparator is serializable.
   *
   * <p><b>Java 8+ users:</b> Use {@code Comparator.comparing(Object::toString)} instead.
   */
  @GwtCompatible(serializable = true)

  echo JAVA_HOME is set to "%JAVA_HOME%", but "%%JAVA_HOME%%\bin\java.exe" does not exist. >&2
  goto error
)

:checkJavaCmd
if not exist "%JAVACMD%" (
  echo The java.exe command does not exist in PATH nor is JAVA_HOME set, so Apache Maven cannot be started. >&2
  goto error
)
:chkMHome
set "MAVEN_HOME=%~dp0"
set "MAVEN_HOME=%MAVEN_HOME:~0,-5%"

need it so that empty directory does not get deleted...