title: SpringTemplateEngine.process doesn't read file (thymeleaf)
body: <p>I'm trying to use a Thymeleaf template engine to create an html email, by following <a href="https://memorynotfound.com/spring-mail-sending-email-thymeleaf-html-template-example/" rel="nofollow noreferrer">this tutorial</a>.</p>
  
  <p>I've created the template configuration:</p>
  
  <pre><code>import org.springframework.context.annotation.Bean;
  import org.springframework.context.annotation.Configuration;
  import java.nio.charset.StandardCharsets;
  import org.thymeleaf.spring5.SpringTemplateEngine;
  import org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver;
  import org.thymeleaf.templatemode.TemplateMode;
  
  
  @Configuration
  public class ThymeleafTemplateConfiguration {
    @Bean
    public SpringTemplateEngine springTemplateEngine() {
      SpringTemplateEngine templateEngine = new SpringTemplateEngine();
      templateEngine.addTemplateResolver(htmlTemplateResolver());
      return templateEngine;
    }
  
    @Bean
    public SpringResourceTemplateResolver htmlTemplateResolver(){
      SpringResourceTemplateResolver templateResolver = new SpringResourceTemplateResolver();
      templateResolver.setPrefix("/templates/");
      templateResolver.setSuffix(".html");
      templateResolver.setTemplateMode(TemplateMode.HTML);
      templateResolver.setCharacterEncoding(StandardCharsets.UTF_8.name());
      return templateResolver;
    }
  }
  </code></pre>
  
  <p>and an html template:</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html lang="en"&gt;
  &lt;head&gt;
    &lt;meta charset="UTF-8"&gt;
    &lt;title&gt;Title&lt;/title&gt;
  &lt;/head&gt;
  &lt;body&gt;
    &lt;p&gt;This is the body to be changed&lt;/p&gt;
    &lt;p&gt;This is a name: ${name}&lt;/p&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>Then I try to populate the template:</p>
  
  <pre><code>templateEngine = new SpringTemplateEngine();
  Context context = new Context();
  context.setVariable("name", "my name");
  
  String html = templateEngine.process("index", context);
  System.out.println(html);
  </code></pre>
  
  <p>But rather than getting the populated template, I'm just getting the first parameter I put into process:</p>
  
  <pre><code>&gt;&gt;&gt; my name
  </code></pre>
  
  <p>What am I doing wrong? why does process take the parameter as-is rather than reading the file with the specified prefix and suffix? (/templates/index.html)</p>