There is a need to upgrade JavaEE Cartridge to version 5.9.12 to be able support WebSphere v.9 , but unfortunately, there are still those running WebSphere v.7.0.x instances which are currently being monitored.
Referring to the System Support guide for the JavaEE Cartridge, the last version of JavaEE Cartridge was 5.9.11 which supported WebSphere v.7.0.x. To monitor the WebSphere v.9 instances, there is a need to upgrade to JavaEE 5.9.12.
1. Is the Java agent 5.9.11 backward compatible to JavaEE 5.9.12 and Nexus 5.9.12 on FMS side ?
2. Is it possible to leave the Java agent to run 5.9.11 for those WebSphere 7.0.x and upgrade to JavaEE 5.9.12 only for those running WebSphere 8.x and 9.x?
Yes to both questions. Simply upgrade Java cart to 5.9.12 and Nexus will also get auto-upgraded. You can then pick and choose only those hosts where agent need to be upgraded to 5.9.12 and leave those 5.9.11 installations as is.