docs: @Override
      public Date requeue(final long index) {
          Date retryDate = null;
          final List<JobFailure> failures = getFailures(index, 1);
          if (!failures.isEmpty()) {
              retryDate = PoolUtils.doWorkInPoolNicely(this.jedisPool, new PoolWork<Jedis, Date>() {
                  /**
                   * {@inheritDoc}
                   */
                  @Override
                  public Date doWork(final Jedis jedis) throws Exception {
                      final Date retriedAt = new Date();
                      final JobFailure failure = failures.get(0);
                      failure.setRetriedAt(retriedAt);
                      jedis.lset(key(FAILED), index, ObjectMapperFactory.get().writeValueAsString(failure));
                      enqueue(jedis, failure.getQueue(), failure.getPayload());
                      return retriedAt;
                  }
              });
          }
          return retryDate;
      }