JAM plugin is not listed under "show version" plugin list. It is not specifically installed. However such messageson boot up operation starting in 21.4R3-S5.4. In previous versions no JAM messages were seen.

These init messages are expected and seen during boot time. It is needed to debug if issue occur on the platform that is supported..

If JAM are seen on non supported platforms - like QFX, these messages can be ignored