code: static RolloutOptions rolloutOptionsWithFallback(final RolloutOptions options, final Job job) {
      return options.withFallback(
          job.getRolloutOptions() == null
          ? RolloutOptions.getDefault()
          : job.getRolloutOptions().withFallback(RolloutOptions.getDefault()));
    }
docs: Returns a {@link RolloutOptions} instance that will replace null attributes in options with
  values from two tiers of fallbacks. First fallback to job then
  {@link RolloutOptions#getDefault()}.