Client-side form: Required indicator is not shown at page load when adding a client-side required validator

[haijian-vaadin]

After adding a client-side validator that indicates the field should be required (NotEmpty, NotNull etc), e.g., this.binder.for(firstname).addValidator(new NotEmpty()); The indicator is not shown on page load, but once the field is visited, the indicator is shown.

Meanwhile, adding a server-side annotation would show the required indicator already on page load.