azure-sdk-for-go: Evenhub Disaster Recovery Config with alternate name cannot be deleted

Bug Report

• import path of package in question, e.g. .../services/compute/mgmt/2018-06-01/compute "github.com/Azure/azure-sdk-for-go/services/eventhub/mgmt/2017-04-01/eventhub"
• SDK version e.g. master, latest, 18.1.0
  • Specify the exact commit if possible; one way to get this is the REVISION column output by dep status "github.com/Azure/azure-sdk-for-go.

github.com/Azure/azure-sdk-for-go v33.2.0+incompatible
github.com/hashicorp/go-azure-helpers v0.7.0

• output of go version go version go1.12.6 darwin/amd64

• What happened? Once an alternate name has been assigned to an eventhub DRC it doesn’t seem possible to delete it via the SDK: Error: errors during apply: Error issuing delete request for EventHub Namespace Disaster Recovery Configs "acctest-EHN-190925153556128780-a" (Namespace "acctest-EHN-190925153556128780-a" / Resource Group "acctestRG-190925153556128780"): eventhub.DisasterRecoveryConfigsClient#Delete: Failure responding to request: StatusCode=400 -- Original Error: autorest/azure: Service returned an error. Status=400 Code="BadRequest" Message="Cannot delete as Alias and Primary Namespace are same. CorrelationId: 7ec915de-1460-8a33-edc2-0e4e16faa34b"

And removing the alternative name doesn’t seem to be possible: Error: Error creating/updating EventHub Namespace Disaster Recovery Configs "acctest-EHN-190925181808103471-a" (Namespace "acctest-EHN-190925181808103471-a" / Resource Group "acctestRG-190925181808103471"): eventhub.DisasterRecoveryConfigsClient#CreateOrUpdate: Failure responding to request: StatusCode=400 -- Original Error: autorest/azure: Service returned an error. Status=400 Code="LinkedInvalidPropertyId" Message="Property id '' at path 'properties.partnerNamespace' is invalid. Expect fully qualified resource Id that start with '/subscriptions/{subscriptionId}' or '/providers/{resourceProviderNamespace}/'."

• What did you expect or want to happen? the DRC to be deleted

• How can we reproduce it? assign a alternative name to a DRC and attempt to delete it (after breaking the pair)

• Anything we should know about your environment.