code: public void saveProperty(T property, String value) throws IOException
      {
          setProperty(property, value);
          saveProperty(property);
      }
docs: Modify the value of the given property and save <b>only that change</b>
  to permanent storage. This method will not save other properties whose
  values may have been modified since the file was last loaded or saved.
  Any modifications that have been made to other properties will still be
  set, but the file will not reflect those changes until {@link #save()} or
  {@link #saveNB()} is called.<br>
  <br>
  Note that there is no guarantee that the modification and saving will be
  atomic. In other words, it is possible that this call will modify the
  value, another call will further change the value, and then the property
  will be saved.
  
  @param property
  the property whose value is being saved
  @param value
  the value to save
  @throws IOException
  if there is an error while attempting to write the property
  to the file