docs: private void initFlushOperation(String bulkLoggingID, boolean retryOperation, long retriedDocs, long waitTime) {
          if (retryOperation) {
              if (waitTime > 0L) {
                  debugLog(bulkLoggingID, "Retrying [%d] entries after backing off for [%s] ms",
                          retriedDocs, TimeValue.timeValueMillis(waitTime));
                  try {
                      Thread.sleep(waitTime);
                  } catch (InterruptedException e) {
                      debugLog(bulkLoggingID, "Thread interrupted - giving up on retrying...");
                      throw new EsHadoopException("Thread interrupted - giving up on retrying...", e);
                  }
              } else {
                  debugLog(bulkLoggingID, "Retrying [%d] entries immediately (without backoff)", retriedDocs);
              }
          } else {
              debugLog(bulkLoggingID, "Sending batch of [%d] bytes/[%s] entries", data.length(), dataEntries);
          }
      }