The display name of Azure Policy assignment is optional or not

According to the document: https://learn.microsoft.com/en-us/cli/azure/policy/assignment?view=azure-cli-latest#az-policy-assignment-create-optional-parameters & https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/subscription_policy_assignment, **--display-name** is an optional parameter for Azure Policy Assignment.

However, the assignment name is required in Azure Portal. Yes, we can deploy the policy without display-name successfully. It is pretty confused for users since they see different behaviours in Azure Portal. Any ideas?

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#### Document Details

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* ID: 1c6760bb-c278-da56-a95c-4e82e221f1e8
* Version Independent ID: e25cbd2a-b415-214f-7d50-c403992c9361
* Content: [az policy assignment](https://learn.microsoft.com/en-us/cli/azure/policy/assignment?view=azure-cli-latest)
* Content Source: [latest/docs-ref-autogen/policy/assignment.yml](https://github.com/MicrosoftDocs/azure-docs-cli/blob/main/latest/docs-ref-autogen/policy/assignment.yml)
* Service: **azure-resource-manager**
* GitHub Login: @rloutlaw
* Microsoft Alias: **routlaw**