he origin server did not find a current representation for the target resource or is not willing to disclose that one exists.

Boa tarde a todos

Construí uma pequena aplicação spring apenas para fins de aprendizado e estou tentando executa-la com o tomcat, já tentei de tudo e sempre recebo o erro 404. Alguém saberia me explicar qual o problema?

package com.fred.springboot;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;

@SpringBootApplication
public class SpringbootApplication extends SpringBootServletInitializer {

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

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder builder) {
        return builder.sources(SpringbootApplication.class);
    }

}

package com.fred.springboot.controller;

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

@RestController("/")
public class HelloController {

    @GetMapping
    public String helloMsg() {
        return "WAR: Hello java spring-boot!!!";
    }

}

<?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>2.4.3</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.fred</groupId>
    <artifactId>springboot</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot</name>
    <description>Demo project for Spring Boot</description>

    <packaging>war</packaging>

    <properties>
        <java.version>15</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>