code: public void validateNotNull(Object object, String name, String message) {
          if (object == null) {
              addError(name, Optional.ofNullable(message).orElse(messages.get(Validation.NOTNULL_KEY.name(), name)));
          }
      }
docs: Validates a given object to be not null
  
  @param object The object to check
  @param name The name of the field to display the error message
  @param message A custom error message instead of the default one