plugins {

    id 'org.springframework.boot' version '2.1.5.RELEASE'

    id 'java'

}

apply plugin: 'io.spring.dependency-management'

group = 'com.example'

version = '0.0.1-SNAPSHOT'

sourceCompatibility = '1.8'

apply plugin: 'war'

repositories {

    mavenCentral()

}

dependencies {

    implementation 'org.springframework.boot:spring-boot-starter-web'

    testImplementation 'org.springframework.boot:spring-boot-starter-test'

    compile group: 'com.google.code.gson', name: 'gson', version: '2.8.2'

    providedRuntime('org.springframework.boot:spring-boot-starter-tomcat')

}

package com.example.demo;

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 DemoApplication extends SpringBootServletInitializer {

    @Override

    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {

        return application.sources(DemoApplication.class);

    }

    public static void main(String[] args) {

        SpringApplication.run(DemoApplication.class, args);

    }

}