private NoteProvider getNoteProvider(boolean changed) {
   NoteProvider provider = session.get(NoteProvider.class);
   if (provider == null) {
     provider = new NoteProvider();
     session.set(provider);
   } else if (changed) {
     setChanged();
   }
   return provider;
 }
 public void storeNote(String id, String title, String content) {
   NoteHeader note = getNoteProvider(false).getNote(id);
   if (note != null) {
     setChanged();
     note.setTitle(title);
     session.set(id, content);
     listeners.noteChanced(id);
   }
 }
 private void setChanged() {
   session.set(session.get((NoteProvider.class)));
 }
 public String getNoteContent(String id) {
   return id == null ? null : session.get(id, String.class);
 }
 public void addNote(String title, String content) {
   String id = getNoteProvider(true).addNote(title, content);
   session.set(id, content);
   listeners.noteAdded(id);
 }