make sure provisioning readonly is readonly

Should the "Read only" = "True" setting under the Advanced settings in the provisioner config cause it to just be calculating what changes are to be made and logging them? I had encountered the above issue when I tried it in 2.6.9, so I thought I would just do a dry run which would log potential adds and deletes to verify how things would run without actually making any changes in the target. However the logs were showing a bunch of HTTP 400 errors like
grouper-daemon;grouper_error.log;unt${env:USERTOKEN}2022-09-14T17:28:15,491: [DefaultQuartzScheduler_Worker-8] ERROR GrouperProvisioningLogCommands.errorLog(50) - [] - Comm
and log for provisioner 'azureTestAdsO365LicenseProvisioner' - 'vhq498ym', deleteMembership: HTTP method: delete
...
(vhq498ym): Caused by: java.lang.RuntimeException: Invalid return code '400', expecting: 204, 404.
Fortunately this is our "test" instance.