"collision in threads table" using CompletableFutures and Java 16+

[KristofferSmedlund]

In Java 17, a security fix was applied. All tasks that are executed within ForkJoinPool.commonPool will clear all ThreadLocal data for that thread after the task is completed.

This breaks the way that the scalyr-logback appender handles multi threaded logging since the EventUploader.java class has the state for the thread in its map but the Events.java class cant find it's threadlocal value. It ends in the assert giving an error with the message "collision in threads table".

Logstash logback appender has already solved this:
logfellow/logstash-logback-encoder#722