docs: public void flush() throws IOException {
          if (unflushed.get() == 0) return;
  
          synchronized (lock) {
              if (logger.isTraceEnabled()) {
                  logger.debug("Flushing log '" + name + "' last flushed: " + getLastFlushedTime() + " current time: " + System
                          .currentTimeMillis());
              }
              segments.getLastView().getMessageSet().flush();
              unflushed.set(0);
              lastflushedTime.set(System.currentTimeMillis());
          }
      }