code: public List<ValidationError> validateInput() {
          List<ValidationError> errors = new ArrayList<>();
          Object value = getModel().getValue(getName());
          ValidationError error;
          for (InputValidator validator : validators) {
              error = validator.validate(value, getName(), getLabel());
              if (error != null){
                  errors.add(error);
              }
          }
          return errors;
      }
docs: Runs a validation on the user input and returns all the validation errors of this field.
  Previous error messages are removed when calling {@code validateInput()}.
  
  @return  a list containing all the validation errors