@Override
  @CheckForNull
  public EmailMessage format(Notification notif) {
    if (!(notif instanceof ChangesOnMyIssuesNotification)) {
      return null;
    }

    ChangesOnMyIssuesNotification notification = (ChangesOnMyIssuesNotification) notif;

    if (notification.getChange() instanceof AnalysisChange) {
      checkState(!notification.getChangedIssues().isEmpty(), "changedIssues can't be empty");
      return formatAnalysisNotification(notification.getChangedIssues().keySet().iterator().next(), notification);
    }
    return formatMultiProject(notification);
  }
@Test
  public void format_returns_null_on_Notification() {
    EmailMessage emailMessage = underTest.format(mock(Notification.class));

    assertThat(emailMessage).isNull();
  }