Slot `id` on class `Entity` is not required

[eecavanna]

When looking at the schema docs yesterday, I noticed the id slot on the Entity class was not required.

I looked at the YAML source code and saw # required: true is commented out.

bertron-schema/src/schema/linkml/bertron_schema.yaml

Lines 57 to 67 in 4ee7dfd

	id:
	aliases:
	- BER data source internal identifier
	- CURIE
	description: The unique ID used for the entity within the BER resource. It may not necessarily be resolvable outside the resource.
	comments:
	- If the data source does not use CURIEs, we cannot guarantee that IDs will be unique between all the BER sources.
	# identifier: true
	# required: true
	range: string
	slot_uri: schema:identifier

I discussed this with @shreddd and he mentioned that the JSON-to-Mongo ingester is implemented under the assumption that each entity has an id.

I think there is an inconsistency in our system here.

[shreddd]

We are indexing on id as the unique key now, so we should make this required.