code: public ConditionMessage append(String message) {
  		if (!StringUtils.hasLength(message)) {
  			return this;
  		}
  		if (!StringUtils.hasLength(this.message)) {
  			return new ConditionMessage(message);
  		}
  
  		return new ConditionMessage(this.message + " " + message);
  	}
docs: Return a new {@link ConditionMessage} based on the instance and an appended
  message.
  @param message the message to append
  @return a new {@link ConditionMessage} instance