      Three basic permissions -- add, change and delete -- are automatically
      created for each Django model.
      """
      name = models.CharField(_('name'), max_length=255)
      content_type = models.ForeignKey(ContentType, verbose_name=_('content type'))
      codename = models.CharField(_('codename'), max_length=100)
      objects = PermissionManager()
  
      class Meta:
          verbose_name = _('permission')
 
</s> remove             content_type = models.ForeignKey(ContentType, null=True)
 </s> add             content_type = models.ForeignKey(ContentType, models.SET_NULL, null=True) </s> remove             content_type = models.ForeignKey(ContentType)
 </s> add             content_type = models.ForeignKey(ContentType, models.CASCADE) </s> remove     site = models.ForeignKey(Site, related_name="admin_articles")
 </s> add     site = models.ForeignKey(Site, models.CASCADE, related_name="admin_articles") </s> remove     content_type = models.ForeignKey(ContentType)
 </s> add     content_type = models.ForeignKey(ContentType, models.CASCADE) </s> remove     user = models.ForeignKey(settings.AUTH_USER_MODEL, verbose_name=_('user'))
    content_type = models.ForeignKey(ContentType, verbose_name=_('content type'), blank=True, null=True)
 </s> add     user = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        models.CASCADE,
        verbose_name=_('user'),
    )
    content_type = models.ForeignKey(
        ContentType,
        models.SET_NULL,
        verbose_name=_('content type'),
        blank=True, null=True,
    )
    content_type = models.ForeignKey(
        ContentType,
        models.CASCADE,
        verbose_name=_('content type'),
    )
      Three basic permissions -- add, change and delete -- are automatically
      created for each Django model.
      """
      name = models.CharField(_('name'), max_length=255)
    content_type = models.ForeignKey(
        ContentType,
        models.CASCADE,
        verbose_name=_('content type'),
    )
      codename = models.CharField(_('codename'), max_length=100)
      objects = PermissionManager()
  
      class Meta:
          verbose_name = _('permission')
keep keep keep keep replace keep keep keep keep keep
 Fixed #21127 -- Started deprecation toward requiring on_delete for ForeignKey/OneToOneField 
django/contrib/auth/models.py