[Question] Property case?

To avoid a lot of copying due to downstream requirements my model uses two properties that begin with lower case letters and gets these two messages from `validate`
```
CloudFormation properties don't usually start with lowercase letters: key
CloudFormation properties don't usually start with lowercase letters: values
```

My contract tests fail in `resource_client.py` with (my logging)
```
WARNING rpdk.core.contract.resource_client:resource_client.py:431 compare_collection: inputs: [{'Key': 'Key1', 'Values': ['Key1-Value1', 'Key1-Value2']}]
WARNING rpdk.core.contract.resource_client:resource_client.py:432 compare_collection: outputs: [{'key': 'Key1', 'values': ['Key1-Value1', 'Key1-Value2']}]
```
With what I'm guessing is a mismatch on the key case difference.

Are properties required to begin with an upper case letter? If so shouldn't `validate` fail? If not then what is changing the key case? (If lower case is valid the Go model generator should note this in the `json` tag).

Thanks.