need to resolve Whitelabel Error with springboot and freemarker templates

Question

I'm new to framemaker and have tried to run this sample project and I'm getting a Whitelabel Error message when I try to access http://localhost:8081/index. In the console the exception is:

javax.servlet.ServletException: Could not resolve view with name 'index' in servlet with name 'dispatcherServlet'

It's not mapping the view properly, but I'm struggling to find out what's wrong.

SpringBootHelloWorldApplication.java

package com.javainuse;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringBootHelloWorldApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringBootHelloWorldApplication.class, args);
    }
}

User.java

package com.javainuse.model;

public class User {
    private String firstname;
    private String lastname;

    public User() {}

    public User(String firstname, String lastname) {
        this.firstname = firstname;
        this.lastname = lastname;

    }

    public String getFirstname() {
        return firstname;
    }

    public void setFirstname(String firstname) {
        this.firstname = firstname;
    }

    public String getLastname() {
        return lastname;
    }

    public void setLastname(String lastname) {
        this.lastname = lastname;
    }

}

WebConfig.java

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;
import org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer;
import org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver;

@EnableWebMvc
@Configuration
@ComponentScan(basePackages = "com.javainuse")
public class WebConfig extends WebMvcConfigurationSupport {

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/resources/**").addResourceLocations("/resources/");
    }

    @Bean
    public FreeMarkerViewResolver freemarkerViewResolver() {
        FreeMarkerViewResolver resolver = new FreeMarkerViewResolver();
        resolver.setCache(true);
        resolver.setSuffix(".ftlh");
        return resolver;
    }

    @Bean
    public FreeMarkerConfigurer freemarkerConfig() {
        FreeMarkerConfigurer freeMarkerConfigurer = new FreeMarkerConfigurer();
        freeMarkerConfigurer.setTemplateLoaderPath("/templates/");
        return freeMarkerConfigurer;
    }

}

TestController.java

import java.util.ArrayList;
import java.util.List;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;

import com.javainuse.model.User;

@Controller
@ComponentScan("com.javainuse")
public class TestController {

    private static List<User> userList = new ArrayList<>();

    static {
        userList.add(new User("Bill", "Gates"));
        userList.add(new User("Steve", "Jobs"));
        userList.add(new User("Larry", "Page"));
        userList.add(new User("Sergey", "Brin"));
        userList.add(new User("Larry", "Ellison"));
    }

    @RequestMapping("/welcome")
    public String hello(Model model,
            @RequestParam(value = "name", required = false, defaultValue = "World") String name) {
        model.addAttribute("name", name);
        return "welcome";
    }

    @GetMapping(value = "/index")
    public String index(@ModelAttribute("model") ModelMap model) {

        model.addAttribute("userList", userList);

        return "index";
    }

}

templates/index.ftlh

<html>
<head><title>FreeMarker Spring MVC Hello World</title>
<body>
<div id="header">
<H2>
    FreeMarker Spring MVC Hello World
</H2>
</div>

<div id="content">
    
  <fieldset>
    <legend>Add User</legend>
  <form name="user" action="add.html" method="post">
    Firstname: <input type="text" name="firstname" />   <br/>
    Lastname: <input type="text" name="lastname" /> <br/>
    <input type="submit" value="   Save   " />
  </form>
  </fieldset>
  <br/>
  <table class="datatable">
    <tr>
        <th>Firstname</th>  <th>Lastname</th>
    </tr>
    <#list model["userList"] as user>
    <tr>
        <td>${user.firstname}</td> <td>${user.lastname}</td>
    </tr>
    </#list>
  </table>

</div>  
</body>
</html>