It seems that when I want to extend LogPatternConverter, you quickly get an IllegalAccessException. The source of that problem seems to be the method PatternParser.finalizeConverter().
On one hand I should be able to create the static newInstance method in my newly created class (variable "newInstanceMethod"). Otherwise the method is not assigned:
On the other hand, "newInstanceMethod.invoke" is called without calling newInstanceMethod.setAccessible(true)
But your extended class would normally be ourside the package of PatternParser. Triggering an IllegalAccessException.
A possible workaround is to put your new class in the package org.apache.logging.log4j.core.pattern yourself. But that is not how we normally extend classes .