priority to JDK 1.4,  JAVA only support JKS, after 1.4 it start to support JCEKS. So would like to support Keystore type JCEKS for DB2 JDBC driver.

refer to

 https://dev.to/neilmadden/java-keystoresthe-gory-details-dnj 

https://knowledgebase.progress.com/articles/Article/Is-Java-9-supported-with-the-DataDirect-Connect-for-JDBC-drivers 
https://www.pixelstech.net/article/1409966488-Different-types-of-keystore-in-Java----JKS
https://www.pixelstech.net/article/1420439432-Different-types-of-keystore-in-Java----JCEKS
https://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html 
Internet X.509 Public Key Infrastructure : https://www.ietf.org/rfc/rfc3280.txt The Transport Layer Security (TLS) Protocol RFC: https://www.ietf.org/rfc/rfc5246.txt certificate type : https://knowledgebase.progress.com/articles/Article/000028360