Splunk forwarder to add custom fields for multiple logs

I have to setup Splunk for 100 servers, each server will have 5-10 JVMs, Each JVM generates 3-4 log files. I would like to index logs to a central Splunk server and along with data , I would also like to send custom fields. so that I can uniquely search JVM logs or different files. for example a NullPinterException in JVM= "ABC" and in log file Server.log or in jms.log. How can I design the deployment and custom fields? The deployment looks like the following Server A-> JVM 1-> server.log jakarta.log httpd.log jms.log JVM 2-> server.log jakarta.log httpd.log jms.log Server B-> JVM 3-> server.log jakarta.log httpd.log jms.log JVM 4-> server.log jakarta.log httpd.log