[ReleasePR eventhub] Service Bus and EventHub : 2021-06-01-preview  - Added optional Properties (#1873)
[ReleasePR eventhub] Service Bus and EventHub : 2021-06-01-preview  - Added optional Properties (#1873)

Create to sync https://github.com/Azure/azure-rest-api-specs/pull/15233
[ReCreate this PR](https://github.com/azure-resource-manager-schemas/compare/main...AzureSDKAutomation:sdkAuto/eventhub?expand=1)
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