Required. The ObjectId of the requested object.
ObjectId
Returns the field-presence view for this GetObjectRequest instance.
Mask specifying which fields to read. If no mask is specified, defaults to object_id,version,digest.
object_id,version,digest
Request a specific version of the object. If no version is specified, and the object is live, then the latest version of the object is returned.
Copies the original message, including unknown fields.