Serverless.ts: How to use Fn::GetAtt in a Lambda's Stream ARN

In a serverless.ts file, how can I define the Stream ARN in a Lambda?

hello: {
  handler: "src/handler.hello",
  events: [
      stream: {
        arn: { "Fn::GetAtt": ["UsersTable", "StreamArn"] },

Doing it the way above returns an error since the ARN object is being parsed as an array, which is not valid as the ARN requires a string.