[Bug]: Unable to model Polymorphic properties in ARM Patch SYnc

[Abhinav93]

Describe the bug

We have some polymorphic discriminator properties in our typespec. One of the examples beloe

// Polymorphic Source
@discriminator("type")
@doc("The type of backing data source")
model Source {
  @doc("Type of the Storage Connector – Bucket. Not mutable once the Storage Connector is created.")
  type?: SourceType;
}
// Bucket source extends source
@doc("The properties of the backing data store.")
model BucketSource extends Source {
  @visibility("read")
  type: SourceType.Bucket;
  @doc("Details for how to connect to the backing data store.")
  connection: Connection;
  @doc("Details for how to authenticate to the backing data store.")
  authProperties: AuthProperties;
  @doc("The host to use when computing the signature for requests to the backing data store. If not provided, defaults to what is provided in the endpoint for the connection.")
  hostOverride?: string;
}
// The actual connector properties 
@doc("Details of the Storage Connector.")
model ConnectorProperties {
  @visibility("read", "create")
  @doc("System-generated identifier for the Storage Connector. Not a valid input parameter when creating.")
  uniqueId?: string;
  @doc("State – Enabled or Disabled. Whether or not the Storage Connector should start as enabled (default: Enabled) (While set to false on the Storage Connector, all data plane requests using this Storage Connector fail, and this Storage Connector is not billed if it would be otherwise.)")
  state?: State = State.Enabled;
  @visibility("read", "create")
  @doc("System-generated creation time for the Storage Connector. Not a valid input parameter when creating.")
  creationTime?: string;
  @doc("Arbitrary description of this Storage Connector. Max 250 characters.")
  @maxLength(250)
  description?: string;
  @doc("Information about how to communicate with and authenticate to the backing data store.")
  source: Source;
  @visibility("read")
  @doc("The status of the last operation.")
  provisioningState?: ProvisioningState;
}
// Conenctor resource as tarcked resource
@doc("A Connector is a tracked ARM resource modeled as a sub-resource of a Storage Account")
model Connector is TrackedResource<ConnectorProperties> {
  @doc("The name of the connector")
  @pattern("^[a-zA-Z0-9-]{3,24}$")
  @key("connectorName")
  @segment("connectors")
  @path
  name: string;
}
When adding a update patch method for this resource -
@armResourceOperations(Connector)
interface Connectors {
  @doc("Get the specified Storage Connector.")
  get is ArmResourceRead<Connector>;
  @doc("Create or update a Storage Connector.")
  createOrReplace is ArmResourceCreateOrReplaceAsync<Connector>;
  @doc("Update a Storage Connector.")
  update is ArmCustomPatchAsync<
    Connector,
    ConnectorProperties
    >;
}

We see an error from swagger Lint DIff validation stating that all properties of a patch resource should be optional.
Typespec does not allow us to have optional discriminator values
Is there a way we can model this in typespec for patch api?

Reproduction

Model the above in typesepc with ARM patch sync to reproduce this error

Checklist

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