og_subgroups.php

<?php

  /**
   * Get the parent groups of an entity.
   *
   * @param \Drupal\Core\Entity\EntityInterface $entity
   *   The entity objects.
   * @param array $groups
   *   Array of group entities passed by reference.
   *
   * @return array
   *   Array of group entities.
   */
  protected function getParentGroups(EntityInterface $entity, &$groups = []) {
    $fields = OgGroupAudienceHelper::getAllGroupAudienceFields($entity->getEntityTypeId(), $entity->bundle());

    if (Og::isGroup($entity->getEntityTypeId(), $entity->bundle())) {
      $groups[] = $entity;
    }


    if (!$fields) {
      // We have reached the top level group, that doesn't have audience fields.
      return $groups;
    }

    foreach ($fields as $field) {
      $field_name = $field->getName();
      $group = $entity->{$field_name}->entity;
      self::getParentGroups($group, $groups);
    }
    return $groups;
  }

  /**
   * Determine if user access based on atleast one group.
   *
   * @param \Drupal\Core\Entity\EntityInterface $entity
   *   The group contnt entity.
   *
   * @return bool
   *   TRUE if user has access, FALSE otherwise.
   */
  protected function hasAccessByGroupParents(EntityInterface $entity) {
    $groups = $this->getParentGroups($entity);


    /** @var \Drupal\og\OgAccessInterface $og_access */
    $og_access = \Drupal::service('og.access');

    // Check access of a user.
    foreach ($groups as $group) {
      $access = $og_access->userAccess($group, 'some permission');
      if ($access->isAllowed()) {
        return TRUE;
      }
    }

    return FALSE;
  }

Should return $access here?