code: public void apply(FaceletContext ctx, UIComponent parent) throws IOException, FacesException, FaceletException,
              ELException
      {
          if (!ComponentHandler.isNew(parent))
          {
              return;
          }
          if (parent instanceof EditableValueHolder)
          {
              applyAttachedObject(ctx.getFacesContext(), parent);
          }
          else if (UIComponent.isCompositeComponent(parent))
          {
              FaceletCompositionContext mctx = FaceletCompositionContext.getCurrentInstance(ctx);
              mctx.addAttachedObjectHandler(parent, this);
          }
          else
          {
              throw new TagException(this.tag,
                      "Parent not composite component or an instance of EditableValueHolder: " + parent);
          }
      }
docs: See taglib documentation.
  
  @see javax.faces.view.facelets.FaceletHandler#apply(javax.faces.view.facelets.FaceletContext, javax.faces.component.UIComponent)