code: public boolean validate(boolean show) {
          fireEvents = false;
          for (HasValidators<?> field : fields.keySet()) {
              field.validate(show);
          }
          fireEvents = true;
          updateStateAndNotify();
          return groupValid;
      }
docs: Validate the group. This calls {@link Validator #validate(Editor, Object)} on each field in the group.
  
  @param show do we want to show the user the result of the validate via ui marks?
  @return true, if successful