code: public void setParent(HierarchicalFormModel parent) {
  		Assert.notNull(parent, "parent");
  		this.parent = parent;
  		this.parent.addPropertyChangeListener(ENABLED_PROPERTY, parentStateChangeHandler);
  		this.parent.addPropertyChangeListener(READONLY_PROPERTY, parentStateChangeHandler);
  		enabledUpdated();
  		readOnlyUpdated();
  	}
docs: {@inheritDoc}
  
  When the parent is set, the enabled and read-only states are bound and
  updated as needed.