add checkExists in deleteJob

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import java.util.Calendar;

import java.util.*;

import java.util.Calendar;

import java.util.concurrent.locks.ReadWriteLock;

import java.util.concurrent.locks.ReentrantReadWriteLock;

  public boolean deleteJob(String jobName, String jobGroupName) {

    lock.writeLock().lock();

    try {

      JobKey jobKey = new JobKey(jobName,jobGroupName);

      if(scheduler.checkExists(jobKey)){

        logger.info("try to delete job, job name: {}, job group name: {},", jobName, jobGroupName);

      return scheduler.deleteJob(new JobKey(jobName, jobGroupName));

        return scheduler.deleteJob(jobKey);

      }

    } catch (SchedulerException e) {

      logger.error(String.format("delete job : %s failed",jobName), e);

    } finally {