Enum path parameter cause generate incorrect code

[VeryEarly]

await this.Client.DirectLineRegenerateKeys(InputObject.ResourceGroupName ?? null, InputObject.ResourceName ?? null, InputObject.SubscriptionId ?? null, InputObject.ChannelName ?? ((Microsoft.Azure.PowerShell.Cmdlets.BotService.Support.ChannelName)""), Parameter, onOk, onDefault, this, Pipeline);

ChannelName is enum, '??' cannot be applied to value type (e.g. enum, int)

[dolauli]

@VeryEarly Please add more details for this issue.