private static JobContext newJobContext(JobConf job) {
    JobID jobID = Optional.ofNullable(JobID.forName(job.get(JobContext.ID)))
                          .orElseGet(JobID::new);

    return new JobContextImpl(job, jobID);
  }
Configures the {@code JobConf} to use the {@code MapredIcebergInputFormat} and
returns a helper to add further configuration.

@param job the {@code JobConf} to configure
iceberg/iceberg-handler/src/main/java/org/apache/iceberg/mr/mapred/MapredIcebergInputFormat.java