code: @Override
      public synchronized void flush() {
          if (trouble) {
              return;
          }
  
          if (isDestinationActivated()) {
              try {
                  getOut().flush();
              }
              catch (IOException e) {
                  handleIOException(e);
              }
          }
      }
docs: Flush the stream.
  
  @see #checkError()