Key Field includes Unwanted Double Quotes

Hello, tried the [new-orders](https://github.com/awslabs/amazon-msk-data-generator/blob/main/examples/new-orders.json) example. I the consumed the events and printed the keys. I noticed the `key` field includes the double quote, which is not correct. Tried different expressions such as `"#{Internet.uuid}"`, same issue

```
{
partition: 0,
key: '"1391037731"',
offset: '0',
value: '{"favorite_beer":"Sublimely Self-Righteous Ale","gender":"Female","name":"Ruben Miller","state":"Maryland"}'
}
```

Start by running the examples/new-orders.json example and reproducing the consumed event shown in the issue. Trace how the key expression is processed, then verify that the consumed key no longer includes surrounding double quotes while the value remains correctly formatted.

Written by the indexing model from the issue text.