code: public static void addBindingUpdateError( ServletRequest request, String expression, String message, Throwable cause )
      {
          Map errors = ( Map ) request.getAttribute( BINDING_UPDATE_ERRORS_ATTR );
  
          if ( errors == null )
          {
              errors = new LinkedHashMap();
              request.setAttribute( BINDING_UPDATE_ERRORS_ATTR, errors );
          }
  
          errors.put( expression, new BindingUpdateError( expression, message, cause ) );
      }
docs: Add a BindingUpdateError to the request.
  
  @param request the current ServletRequest.
  @param expression the expression associated with this error.
  @param message the error message.
  @param cause the Throwable that caused the error.