Rotate dynamic relational database credentials of a Spring Boot app when the Hashicorp Vault max_ttl expires

This code example is used in my blog post Heavy Rotation of Relational Hashicorp Vault Database Secrets in Spring on https://secrets-as-a-service.com/.

It ensures that the Spring Boot application is rotating the the dynamic database credentials, whenever they expire. This approach only works for relational databases using HikariCP as connection pool, which only supports JDBC.