isMaster property
A value that indicates that this job is a main job. A main job represents a successful request to create an export job. Main jobs aren't associated with any Snowballs. Instead, each main job will have at least one job part, and each job part is associated with a Snowball. It might take some time before the job parts associated with a particular main job are listed, because they are created after the main job is created.
Implementation
final bool? isMaster;