Need to create custom API Key in AwsAppSync

Hey folks, I need to create few custom API keys in AWSAppSync via terraform. Can it be done or is it always auto generated.

resource "aws_appsync_api_key" "example" {
  api_id  =
  expires = "2018-05-03T04:00:00Z"

Please review the documentation for this resource:

You will find there is no argument for specifying the API key, it is only returned as an attribute, meaning that it is always generated.