code: protected Lock tryLockForRead(long time, TimeUnit unit) throws InterruptedException {
          if (time < 0 || unit == null) {
              return tryLockForRead();
          }
          Lock lock = readLock();
          return lock.tryLock(time, unit) ? lock : null;
      }
docs: Try to lock the BO for read.
  
  @param time
  @param unit
  @return the "read"-lock in "lock" state if successful, {@code null} otherwise
  @throws InterruptedException
  @since 0.10.0