Should the 'holder' identifier be required for 'stream' pallet? Or can this be optional?

[amarts]

Wanted to record the discussion we had offline on this. While in CORD we anonymize every data with idenfiers, having 'holder' data in the extrinsic would still be considered as a data point for correlation.

While it may be a required public information in some registries, or some usecases, it may not be required in some. We need it mostly as optional field, instead of mandatory.