How do I choose the JDK version?

It's just my decision under those conditions at the reference level.

Identify the required JDK version for each configuration.

• ver.2.3.0 (released on 2020/5): JDK14 support (full support for LTS's JDK 8,11)
• ver2.2.0: JDK13 support (full support for LTS's JDKs 8, 11)
  https://spring.io/blog/2020/05/15/spring-boot-2-3-0-available-now
  https://spring.io/blog/2019/10/16/spring-boot-2-2-0

• JDBC: using ojdbc8.jar (supported JDK 8 or later)
  https://docs.oracle.com/en/database/oracle/oracle-database/19/tdpjd/using-java-with-oracle-database.html#GUID-8C73108B-E0F3-4CD5-A813-909B339339BB

• Ver.10 (Alpha): Supported JDK 8 or later
• Ver.9: Supported JDK 8 or later
  https://tomcat.apache.org/whichversion.html

• Oracle JDK: Java 11 and later "Oracle JDK (LTS)" will only be available to users with paid support contracts with Oracle.
• OpenJDK: An open source implementation "OpenJDK" with the same functionality and quality as "Oracle JDK" is released from Java 11 and a binary is provided free of charge.
  　
  Compare each JDK
  https://www.ossnews.jp/compare/Oracle_JDK/OpenJDK

If you summarize it like this, you can see that each product works after JDK8.
However, there is a commercial problem with Java, so if it is JDK11 or later, the function difference between Oracle and OpenJDK can be reduced.
(I think it's equivalent, but if you switch to the Oracle version at the time of official recruitment, you need to verify the operation.)

Based on the above...If you do not want to use new features beyond JDK11
If I were you, I would choose JDK11 for stability.

For your information.