completionMode property
completionMode specifies how Pod completions are tracked. It can be NonIndexed (default) or Indexed.
NonIndexed means that the Job is considered complete when there have been .spec.completions successfully completed Pods. Each Pod completion is homologous to each other.
Indexed means that the Pods of a Job get an associated completion index from 0 to (.spec.completions - 1), available in the annotation batch.kubernetes.io/job-completion-index. The Job is considered complete when there is one successfully completed Pod for each index. When value is Indexed, .spec.completions must be specified and .spec.parallelism must be less than or equal to 10^5. In addition, The Pod name takes the form $(job-name)-$(index)-$(random-string), the Pod hostname takes the form $(job-name)-$(index).
More completion modes can be added in the future. If the Job controller observes a mode that it doesn't recognize, which is possible during upgrades due to version skew, the controller skips updates for the Job.
Implementation
final String? completionMode;