docs: public final ReadOnlyObjectProperty<Entry<T>> recurrenceSourceProperty() {
          if (recurrenceSource == null) {
              recurrenceSource = new ReadOnlyObjectWrapper<Entry<T>>(this, "recurrenceSource") { //$NON-NLS-1$
                  @Override
                  public void set(Entry<T> newEntry) {
                      super.set(newEntry);
                      if (newEntry != null) {
                          setRecurrence(true);
                      } else {
                          setRecurrence(false);
                      }
                  }
              };
          }
  
          return recurrenceSource.getReadOnlyProperty();
      }