Spring Boot 2.1 with Spring Data Kay and MongoDB 3.5.0

DemoApplication.java

package com.example.demo;

import java.util.Collections;

import javax.annotation.PostConstruct;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.data.mongodb.MongoDbFactory;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.core.SimpleMongoDbFactory;
import org.springframework.data.mongodb.core.convert.DbRefResolver;
import org.springframework.data.mongodb.core.convert.DefaultDbRefResolver;
import org.springframework.data.mongodb.core.convert.MappingMongoConverter;
import org.springframework.data.mongodb.core.convert.MongoConverter;
import org.springframework.data.mongodb.core.convert.MongoCustomConversions;
import org.springframework.data.mongodb.core.mapping.MongoMappingContext;

import com.mongodb.MongoClient;

@SpringBootApplication
public class DemoApplication {

	@Autowired PersonRepository personRepository;

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

	@PostConstruct
	private void postConstruct() {
		personRepository.save(new Person());
		personRepository.findAll();
	}

	@Bean
	public MongoDbFactory mongoDbFactory() {
		MongoClient preferredClient = new MongoClient();
		return new SimpleMongoDbFactory(preferredClient, "test");
	}

	@Bean
	public MongoTemplate mongoTemplate(MongoDbFactory mongoDbFactory, MongoConverter converter) {
		return new MongoTemplate(mongoDbFactory, converter);
	}

	@Bean
	public MappingMongoConverter mappingMongoConverter(MongoDbFactory factory, MongoMappingContext context,
			MongoCustomConversions conversions) {
		DbRefResolver dbRefResolver = new DefaultDbRefResolver(factory);
		MappingMongoConverter mappingConverter = new MappingMongoConverter(dbRefResolver, context);
		mappingConverter.setCustomConversions(conversions);
		return mappingConverter;
	}

	@Bean
	public MongoCustomConversions mongoCustomConversions() {
		return new MongoCustomConversions(Collections.emptyList());
	}
}

pom.xml

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>com.example</groupId>
	<artifactId>demo</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>demo</name>
	<description>Demo project for Spring Boot</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.1.0.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<java.version>1.8</java.version>
		<spring-data-releasetrain.version>Kay-SR4</spring-data-releasetrain.version>
		<mongodb.version>3.5.0</mongodb.version>
	</properties>

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

		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<optional>true</optional>
		</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>