With Spring Boot 2.0, the default connection pool for JPA has been changed from Tomcat to HikariCP. Thus it is no longer required to use the configuration property spring.datasource.type as an override to use HikariCP. Using the following dependency will by default use HikariCP:

<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>