code: public <T extends Widget & HasValidators<?>> boolean remove(final T field) {
          fields.remove((HasValidators<?>) field);
          HandlerRegistration reg = registrations.remove((HasValidators<?>) field);
          if (reg != null) {
              reg.removeHandler();
              return true;
          }
          return false;
      }
docs: Removes a field from the validation group.
  
  @param <T> the generic type
  @param field the field
  @return true, if successful