Fix HikariCP Connection Issue

My Java 1.8 application running on Tomcat 9 with Oracle 19c is facing connection pooling issues with HikariCP. We're accumulating dead connections that aren't being closed, and I need an expert to resolve this.

Key Requirements:
- Configure idle timeouts (most critical)
- Set up periodic connection validation (every 30 minutes)
- Implement leak detection

Ideal Skills:
- Java 1.8 and HikariCP expertise
- Tomcat 9 and Oracle 19c familiarity
- Strong troubleshooting and performance optimization skills