docs: @JSFProperty(partialStateHolder=true)
      public Converter getConverter()
      {
          if (_converter != null)
          {
              return _converter;
          }
          ValueExpression expression = getValueExpression("converter");
          if (expression != null)
          {
              return (Converter) expression.getValue(getFacesContext().getELContext());
          }
          return null;
      }