Changes to Retrieve the last executed price and timestamp for each contract in the market ids provided.

added the new BAD_REQUEST enum value to the error_type response property for the response status 400

the response's body type changed from object to no type for status 400

the response property last_executed_prices/additionalProperties/items/last_executed_price became nullable for the status 200

the response property last_executed_prices/additionalProperties/items/timestamp became nullable for the status 200

the data response's property type changed from null to object for status 500

the data response's property type changed from string to string object for status 400

added the non-success response with the status 401

added the non-success response with the status 403

added the non-success response with the status 503