return weakSetValidator();
      }
    }
  }

  // TODO(cpovirk): change parameter order to match other helper methods (Class, Throwable)?
  private static <X extends Exception> void wrapAndThrowExceptionOrError(
      Throwable cause, Class<X> exceptionClass) throws X {
    if (cause instanceof Error) {
      throw new ExecutionError((Error) cause);
    }

    @Nullable private String value = null;
    @Nullable private Throwable failure = null;
    private boolean wasCalled = false;
    private final Object monitor = new Object();

    MockCallback(String expectedValue) {
      this.value = expectedValue;
    }

    public MockCallback(Throwable expectedFailure) {
      this.failure = expectedFailure;
    }

    @Override

    private final Mojo mojo;

    private final Throwable cause;

    public MojoExecutionEvent(MavenSession session, MavenProject project, MojoExecution mojoExecution, Mojo mojo) {
        this(session, project, mojoExecution, mojo, null);
    }

    public MojoExecutionEvent(
            MavenSession session, MavenProject project, MojoExecution mojoExecution, Mojo mojo, Throwable cause) {
        this.session = session;

     * @param content
     * @param error
     */
    void debug(CharSequence content, Throwable error);

    /**
     * Send an exception to the user in the <b>debug</b> error level.<br>
     * The stack trace for this exception will be output when this error level is enabled.
     *
     * @param error
     */
    void debug(Throwable error);

    /**
     * @return true if the <b>info</b> error level is enabled
     */

    private String getReference(Set<Throwable> dejaVu, Throwable exception) {
        String reference = "";
        if (!dejaVu.add(exception)) {
            return reference;
        }

        if (exception != null) {
            if (exception instanceof MojoExecutionException) {
                reference = MojoExecutionException.class.getSimpleName();

                Throwable cause = exception.getCause();

        super(message);
    }

    public AbstractMojoExecutionException(String message, Throwable cause) {
        super(message, cause);
    }

    /**
     * Constructs a new {@code AbstractMojoExecutionException} exception wrapping an underlying {@code Throwable}.
     *
     * @param cause the cause which is saved for later retrieval by the {@link #getCause()} method.

    FluentFuture<?> f =
        FluentFuture.from(immediateFailedFuture(new CustomRuntimeException()))
            .catching(
                Throwable.class,
                new Function<Throwable, Class<?>>() {
                  @Override
                  public Class<?> apply(Throwable input) {
                    return input.getClass();
                  }
                },
                directExecutor());

    public void fatal(final String message, final Throwable t) {
        logger.fatal(message, t);
    }

    @Override
    public boolean isErrorEnabled() {
        return logger.isErrorEnabled();
    }

    @Override
    public void error(final String message) {
        logger.error(message);
    }

    @Override
    public void error(final String message, final Throwable t) {
        logger.error(message, t);
    }

            List<String> path,
            Throwable t) {
        super(message, groupId, artifactId, version, type, classifier, remoteRepositories, path, t);
    }

    public ArtifactResolutionException(
            String message,
            String groupId,
            String artifactId,
            String version,
            String type,
            String classifier,
            Throwable t) {

    }
  }

  private static final class WrapperException extends Exception {
    WrapperException(Throwable t) {
      super(t);
    }
  }

  private static void rethrow(ExecutionException e) throws ExecutionException {
    Throwable wrapper = e.getCause();
    if (wrapper instanceof WrapperException) {
      Throwable cause = wrapper.getCause();
      if (cause instanceof RuntimeException) {