          schema_url=schema_url,
          public=public,
          patterns=patterns,
          generator_class=generator_class,
      )
      urls = [
          url(r'^$', docs_view, name='docs-index'),
          url(r'^schema.js$', schema_js_view, name='schema-js')
      ]
 
</s> remove         patterns=None, generator_class=SchemaGenerator):
 </s> add         patterns=None, generator_class=SchemaGenerator,
        authentication_classes=api_settings.DEFAULT_AUTHENTICATION_CLASSES,
        permission_classes=api_settings.DEFAULT_PERMISSION_CLASSES):
        authentication_classes=authentication_classes,
        permission_classes=permission_classes,
          schema_url=schema_url,
          public=public,
          patterns=patterns,
          generator_class=generator_class,
        authentication_classes=authentication_classes,
        permission_classes=permission_classes,
      )
      urls = [
          url(r'^$', docs_view, name='docs-index'),
          url(r'^schema.js$', schema_js_view, name='schema-js')
      ]
keep keep keep add keep keep keep keep keep
 allow custom authentication and permission classes for docs view 
rest_framework/documentation.py