Spring Boot + Hibernate没有对多个数据源使用正确的方言

# 主数据源配置
spring.datasource.url=jdbc:mysql://localhost:3306/main_db
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

# 第二个数据源配置
spring.datasource.secondary.url=jdbc:mysql://localhost:3306/secondary_db
spring.datasource.secondary.username=root
spring.datasource.secondary.password=123456
spring.datasource.secondary.driver-class-name=com.mysql.jdbc.Driver

# 主数据源方言配置
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect

# 第二个数据源方言配置
spring.jpa.properties.hibernate.secondary.dialect=org.hibernate.dialect.MySQL5Dialect

@Configuration
public class DataSourceConfig {

    @Primary
    @Bean(name = "mainDataSource")
    @ConfigurationProperties(prefix = "spring.datasource")
    public DataSource mainDataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean(name = "secondaryDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.secondary")
    public DataSource secondaryDataSource() {
        return DataSourceBuilder.create().build();
    }
}

@Service
public class UserService {

    @Autowired
    @Qualifier("mainDataSource")
    private DataSource mainDataSource;

    @Autowired
    @Qualifier("secondaryDataSource")
    private DataSource secondaryDataSource;

    // ...
}