code: public long getTimeSpentInQueue() {
          lock.readLock().lock();
          try {
              return startTime - workUnit.context.item.buildableStartMilliseconds;
          } finally {
              lock.readLock().unlock();
          }
      }
docs: Returns the number of milli-seconds the currently executing job spent in the queue
  waiting for an available executor. This excludes the quiet period time of the job.
  @since 1.440