I'm trying to print Hello World with Spring Boot and want to fix a login window

Question

Hello? I'm a developer trying to study Spring Boot.
For now, I just wanted to print Hello World on a web page, so I created a controller package and a class.
I will post the entire code first.

First is the pom.xml file.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.8.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.limsrs</groupId>
<artifactId>testproject</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>testproject</name>
<description>testproject for Spring Boot</description>

<properties>
    <java.version>1.8</java.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

</project>

Next is the TestprojectApplication.java file.

package com.limsrs.testproject;

import java.util.Arrays;

import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;

@SpringBootApplication
public class TestprojectApplication {

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

    @Bean
    public CommandLineRunner commandLineRunner(ApplicationContext context) {
        return args -> {
            System.out.println("Let's inspect the beans provided by Spring Boot:");

            String[] beanNames = context.getBeanDefinitionNames();
            Arrays.sort(beanNames);
            for (String beanName : beanNames) {
                System.out.println(beanName);
            }
        };
    }
}

Last is the HelloWorldController.java file.

package com.limsrs.testproject.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloWorldController {

    @RequestMapping("/")
    public String home() {
        return "Hello World~!";
    }
}

After running the spring boot app, I tried to connect to localhost: 8080 and the login window appeared.
If you search the Internet, you will see the login method using spring-security, but not that, and you will not see the Hello World screen.

What I want to do is simply see the Hello World screen. The login window is not what I want.