title: Append to a file in JavaIoFileSystemAccess
body: <p>How do I append text to a file in JavaIoFileSystemAccess?</p>
  
  <p>I have tried calling the generateFile with the same filename, but it just overwrites the content of the file. </p>
  
  <p>Is there a setting or method I can call to be able to append contents to a file?</p>