Spring Boot + Thymeleaf not finding message properties
<p>I am trying to create a web application using Spring Boot and Thymeleaf and am having trouble getting the template to use the messages defined in a properties file. Instead of the message defined in the properties file, it is instead showing <code>??form.welcome_en_GB??</code> The console isn't logging any errors.</p>

<p>The project structure is like this</p>

<pre><code>──┬  src
  │   └───  main
  │       ├───  java
  │       │   └───  com
  │       │       └───  package
  │       │           ├───  controller
  │       │           │   └─── FormController.java
  │       │           ├─── Application.java
  │       │           └─── ServletInitializer.java
  │       └───  resources
  │           ├───  static
  │           │   └─── home.html
  │           ├───  templates
  │           │   ├─── form.html
  │           │   └─── form.properties
  │           └─── application.properties
  └─── pom.xml
</code></pre>

<p>Application.java</p>

<pre><code>@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}
</code></pre>

<p>ServletInitializer.java</p>

<pre><code>public class ServletInitializer extends SpringBootServletInitializer {

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(Application.class);
    }
}
</code></pre>

<p>FormController.java</p>

<pre><code>@Controller
@RequestMapping("/form")
public class FormController {
    private static final Logger log = LoggerFactory.getLogger(FormController.class);

    @RequestMapping(value = "/new", method = RequestMethod.GET)
    public ModelAndView getNewReportForm() {
        log.info("New form requested");
        ModelAndView mav = new ModelAndView("form");
        return mav;
    }
}
</code></pre>

<p>form.html</p>

<pre><code>&lt;!DOCTYPE html&gt;
&lt;html xmlns="http://www.w3.org/1999/xhtml" xmlns:th="http://www.thymeleaf.org"&gt;
&lt;head&gt;
    &lt;title&gt;Form&lt;/title&gt;
    &lt;meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/&gt;
    &lt;link rel="stylesheet" type="text/css" media="all"/&gt;
&lt;/head&gt;
&lt;body&gt;
&lt;p th:text="#{form.welcome}"&gt;Welcome!&lt;/p&gt;
&lt;/body&gt;
&lt;/html&gt;
</code></pre>

<p>form.properties</p>

<pre><code>form.welcome=Hello there!
</code></pre>