获取上一次完成的作业执行上下文批处理

我正在尝试获取上次完成作业的执行上下文。代码如下:

@Component
public class MyJobDataReader implements ItemReader<MyDbEntity>, StepExecutionListener {

    @Autowired
    @Qualifier("jobService")
    JobService jobService;

    @Override
    public void beforeStep(StepExecution stepExecution) {
        Collection<JobExecution> jobExecutions = null;
        try {
            jobExecutions = jobService.listJobExecutionsForJob("myjob", 0, jobService.countJobExecutionsForJob("myjob"));
        } catch (NoSuchJobException e) {
            //log
        }

        JobExecution lastCompletedJobExecution =
                jobExecutions
                .stream()
                .filter(param -> param.getExitStatus().getExitCode().equals(ExitStatus.COMPLETED.getExitCode()))
                .findFirst()
                .orElse(null);

        Long myExecutionContextParam = 
                lastCompletedJobExecution
                .getExecutionContext()
                .getLong(contextParam);
    }
}

myExecutionContextParam 也为null,即使我在 BATCH_JOB_EXECUTION_CONTEXT 获取的作业执行的表。