Changes to Make an expert forecast for a news event.

added the optional property sources/items/wikidata_entities/anyOf[subschema #1]/additionalProperties/items/source_mentions to the response with the 200 status

the response property sources/items/centroid_distance became optional for the status 200

the response property sources/items/cluster_probability became optional for the status 200

response property sources/items/centroid_distance list-of-types was widened by adding types null to media type application/json of response 200

response property sources/items/cluster_probability list-of-types was widened by adding types null to media type application/json of response 200

added the optional property sources/items/wikidata_entities to the response with the 200 status