When are connections returned to the connection pool with Spring JPA (Hibernate) Entity Manager?

https://stackoverflow.com/questions/27486104/when-are-connections-returned-to-the-connection-pool-with-spring-jpa-hibernate

https://vladmihalcea.com/a-beginners-guide-to-transaction-isolation-levels-in-enterprise-java/

https://vladmihalcea.com/the-anatomy-of-connection-pooling/