On the java side you can check the JDBC Client Version very easy.
java -jar ./mwhome/.../ojdbc7.jar -getversion Oracle 184.108.40.206.0 JDBC 4.1 compiled with JDK7 on Mon_Jun_30_11:30:34_PDT_2014 #Default Connection Properties Resource #Tue Apr 17 14:13:51 CEST 2018
But somethimes you may not have access to the application server (here Weblogic) or there are many version installed on the application side.
So the best way is to check in you Oracle Database who your client are.
SQL> select SID,NETWORK_SERVICE_BANNER,CLIENT_CHARSET,CLIENT_CONNECTION,CLIENT_VERSION,CLIENT_DRIVER from v$session_connect_info; 396 Crypto-checksumming service for Linux: Version 220.127.116.11.0 - Production Unknown Heterogeneous 18.104.22.168.0 jdbcthin
This is a reliable way to find how (jdbcthin, oci, ..) and with what JDBC Version the client are connecting.