Dynamic properties clarification

Hi,

Currently we've been in the process of integrating OCIO and believe we've encountered an issue regarding the dynamic properties feature.

As far as we understand, they are solely supposed to be handled by the developers and are not intended to be defined or specified as part of the config as stated in the documentation. However when defining an `ExposureContrastTransform`, should a user fail to set a value for a property such as exposure like so:

```
! {style: linear, contrast: 0.5, gamma: 1.1, pivot: 0.18}
```

The generated processor initialises a dynamic property for the missing exposure value. Given that a config is supposed to be locked this seems to contradict the core intention here, therefore we suspect this is a bug and not intentional.

Could you please clarify whether or not this is intended behaviour. If not no worries, we're happy to assist where we can.

Many Thanks

Start by reviewing the dynamic properties documentation and the ExposureContrastTransform behavior shown in the issue. Determine whether a missing exposure value should initialize a dynamic property or be rejected for a locked config, then document the intended behavior or confirm the bug.

Written by the indexing model from the issue text.