public function validateTargetAudienceSettings() {
    $errorMessages = [];

    // @TODO: Enable validation after CRM is updated.
    return [];

    // Age is in the range from Target Audience Setting from Campaign.
    $validateAge = $this->validateMemberAge();
    if (!$validateAge['status']) {
      $errorMessages[] = $validateAge['error'];
    }

    // Member type match Target Audience Setting from Campaign.
    $validateMemberUnitType = $this->validateMemberUnitType();
    if (!$validateMemberUnitType['status']) {
      $errorMessages[] = $validateMemberUnitType['error'];
    }
    // Branch is one of the selected in the Target Audience Setting from Campaign.
    $validateMemberBranch = $this->validateMemberBranch();
    if (!$validateMemberBranch['status']) {
      $errorMessages[] = $validateMemberBranch['error'];
    }

    return $errorMessages;
  }