Why (LEGACY) in "Chapter 10: JMX Configurator" documentation

[freelancer-nguyen]

Hello everyone,

I have been using the jmx configurator feature of LogBack and am very happy with it. However I'm a bit concerned by the (LEGACY) in title of corresponding documentation

https://logback.qos.ch/manual/jmxConfig.html

I cannot find further information about it hence my questions here

1. What does LEGACY mean in this context?
2. If it means feature no longer actively support, then what is the recommended alternative?

Thank you in advance