Some Smack APIs are marked as deprecated in IntelliJ (remove /target, Build Project). They should be replaced with new ones. Usually it is a simple text replacement. New APIs can be found at https://download.igniterealtime.org/smack/docs/latest/javadoc/
Did a few replacements with https://github.com/igniterealtime/Spark/pull/457
A few more replacements https://github.com/igniterealtime/Spark/pull/461
Closing for now. Can do more cleanup in the future.