Fixed #20126 -- XViewMiddleware moved to django.contrib.admindocs.middleware

tests/admin_docs/views.py

@@ -0,0 +1,13 @@
+from django.http import HttpResponse
+from django.utils.decorators import decorator_from_middleware
+from django.views.generic import View
+from django.contrib.admindocs.middleware import XViewMiddleware
+
+xview_dec = decorator_from_middleware(XViewMiddleware)
+
+def xview(request):
+    return HttpResponse()
+
+class XViewClass(View):
+    def get(self, request):
+        return HttpResponse()