django集成swagger报错 TypeError:Expected a `coreapi.Document` instance'

python相关信息

python 3.7.3
django 2.1.8
django-rest-swagger 2.2.0
djangorestframework 3.10.2
coreapi 2.3.3

settings.py文件信息

INSTALLED_APPS = [
…
‘api’,
‘rest_framework’,
‘rest_framework_swagger’,
]

REST_FRAMEWORK = {
‘DEFAULT_PERMISSION_CLASSES’: [
‘rest_framework.permissions.IsAuthenticated’,
]
}

urls.py文件信息

from django.contrib import admin
from django.urls import path
from django.conf.urls import include
from rest_framework import routers
from api import views
from rest_framework.schemas import get_schema_view
from rest_framework_swagger.renderers import SwaggerUIRenderer, OpenAPIRenderer

router = routers.DefaultRouter()
router.register(‘users’, views.UserViewSet, base_name=‘user’)
router.register(‘groups’, views.GroupViewSet, base_name=‘group’)