code: public void writeToFile(final String outputFileName, final boolean blockThread, final boolean shutdownExecutor) {
          if (blockThread) {
              waitForFuturesToBlockCurrentThread();
          }
          super.writeToFile(outputFileName);
  
          if (shutdownExecutor) {
              this.shutdown();
          }
      }
docs: Writes the wordcloud to an imagefile.
  
  @param outputFileName
  some file like "test.png"
  @param blockThread
  should the current thread be blocked
  @param shutdownExecutor
  should the executor be shutdown afterwards. if
  <code>false</code> this PLWC can still be used to build other
  layers. if <code>true</code> this will become a blocking
  Thread no matter what was specified in blockThread.