userId property
Required if allow_missing_ids is unset or false.
A unique user identification string, as determined by the client. To have the strongest positive impact on search quality make sure the client-level is unique. Obfuscate this field for privacy concerns before providing it to the service. Note that any improvements to the model for a particular tenant site rely on this field being set correctly to a unique user ID. The maximum number of allowed characters is 255.
Implementation
core.String? userId;