FieldModuleUninstallValidator::validate

public FieldModuleUninstallValidator::validate($module_name)

public function validate($module) {
  $entity_types = $this->entityManager->getDefinitions();
  $reasons = array();
  foreach ($entity_types as $entity_type) {
    if ($module == $entity_type->getProvider() && $entity_type instanceof ContentEntityTypeInterface && $this->entityManager->getStorage($entity_type->id())->hasData()) {
      $reasons[] = $this->t('There is content for the entity type: @entity_type', array('@entity_type' => $entity_type->getLabel()));
    }
  }
  return $reasons;
}

public function validate($module_name) {
  $reasons = array();

  // We skip fields provided by the Field module as it implements field
  // purging.
  if ($module_name != 'field') {
    foreach ($this->entityManager->getDefinitions() as $entity_type_id => $entity_type) {
      // We skip entity types defined by the module as there must be no
      // content to be able to uninstall them anyway.
      // See \Drupal\Core\Entity\ContentUninstallValidator.
      if ($entity_type->getProvider() != $module_name && $entity_type->isSubclassOf('\Drupal\Core\Entity\FieldableEntityInterface')) {
        foreach ($this->entityManager->getFieldStorageDefinitions($entity_type_id) as $storage_definition) {
          if ($storage_definition->getProvider() == $module_name) {
            $storage = $this->entityManager->getStorage($entity_type_id);
            if ($storage instanceof FieldableEntityStorageInterface && $storage->countFieldData($storage_definition, TRUE)) {
              $reasons[] = $this->t('There is data for the field @field-name on entity type @entity_type', array(
                '@field-name' => $storage_definition->getName(),
                '@entity_type' => $entity_type->getLabel(),
              ));
            }
          }
        }
      }
    }
  }

  return $reasons;
}