docs: public void apply(FaceletContext ctx, UIComponent parent) throws IOException, FacesException, FaceletException,
              ELException
      {
          if (parent == null)
          {
              throw new TagException(this.tag, "Parent UIComponent was null");
          }
  
          // only process if the parent is new to the tree
          if (parent.getParent() == null)
          {
              String n = _name.getValue(ctx);
              if (_value.isLiteral())
              {
                  parent.getPassThroughAttributes().put(n, _value.getValue());
              }
              else
              {
                  parent.getPassThroughAttributes().put(n, _value.getValueExpression(ctx, Object.class));
              }
          }
      }