code: public void awaitCompletion() throws InterruptedException {
      boolean performedWarning = false;
  
      while (hasInflightOperations()) {
        synchronized (signal) {
          if (hasInflightOperations()) {
            signal.wait(finishWaitMillis);
          }
        }
  
        long now = clock.nanoTime();
        if (now >= noSuccessCheckDeadlineNanos) {
          logNoSuccessWarning(now);
          resetNoSuccessWarningDeadline();
          performedWarning = true;
        }
      }
      if (performedWarning) {
        LOG.info("awaitCompletion() completed");
      }
    }
docs: Blocks until all outstanding RPCs and retries have completed
  
  @throws java.lang.InterruptedException if any.