Post Client Flow can add any policy or only message logging policy?

[suchansinee]

I read post client flow from apigee document. they say can add only message logging policy in post client flow.

but from this link https://community.apigee.com/articles/18196/tutorial-apigee-edge-post-client-flow.html they say can add any policies in post client flow

I try to add any policies in post client flow but error has occur

I'm not sure.What is the correct answer?