code: public void expectValue(String name, String message) {
          String value = Optional.ofNullable(get(name)).orElse("");
  
          if (StringUtils.isBlank(StringUtils.trimToNull(value))) {
              addError(name, Optional.ofNullable(message).orElse(messages.get(Validation.REQUIRED_KEY.name(), name)));
          }
      }
docs: Validates a given field to be present with a value
  
  @param name The field to check
  @param message A custom error message instead of the default one