REST: placeholder in Poll URL

The <description> for poll -> Service Endpoints reads "Specify the REST
URLs for the resource. Mention queriable strings as %s."

This sounds like the same approach as the URL Placeholder described in
the documentation, which takes the attribute/value pair in the URL
token element of the driver-operation-data and uses this to replace the
placeholder value during the data transfer.

However, polling seems to be entirely on the shim (with initial config
from init-params/publisher-options. I am at a loss to understand how
one can send the shim driver-operation-data that could be used to
modify the polling.

Can anyone enlighten me as to how this is supposed to work?