@Test
    public void testListChildren() throws Exception {
        String jobId = // ...
        BigQuery bigQuery = BigQueryOptions.getDefaultInstance().getService();
        Iterable<? extends Job> jobChildren = bigQuery.listJobs(
                BigQuery.JobListOption.parentJobId(jobId)
        ).iterateAll();
        for (Job job : jobChildren) {
            job = job.reload(BigQuery.JobOption.fields(BigQuery.JobField.CONFIGURATION, BigQuery.JobField.ID, BigQuery.JobField.STATISTICS, BigQuery.JobField.STATUS));
            LOG.debug("Child job: " + job.getJobId());
            LOG.debug("Child's parent is " + job.getStatistics().getParentJobId());
        }
    }