References:
https://hellokoding.com/jpa-one-to-one-foreignkey-relationship-example-with-spring-boot-maven-and-mysql/
https://hellokoding.com/jpa-one-to-many-relationship-mapping-example-with-spring-boot-maven-and-mysql/
https://hellokoding.com/jpa-many-to-many-relationship-mapping-example-with-spring-boot-maven-and-mysql/
