title: How to include message.properties with thymeleaf
body: <p>I am using spring boot with thymeleaf. This is my project structure: 
  <img src="https://i.stack.imgur.com/kI9MH.png" alt="enter image description here"></p>
  
  <p>And this is my App start class: </p>
  
  <pre><code>    @EnableAutoConfiguration
  @Configuration
  @ComponentScan
  public class App {
      public static void main(String[] args) {
          SpringApplication.run(App.class);
      }
  }
  </code></pre>
  
  <p>I have this on my home.leaf.html: <code>&lt;p th:text = "#{username}"&gt;&lt;/p&gt;</code></p>
  
  <p>But when I run this application this is what I get: ??username_en_US??</p>
  
  <p>I have tried various things on how to resolve this configuration issue. Please, can anyone help?</p>