I guess I understand your intent and below might work for your requirement:
LoggerContext context = new LoggerContext();
context.start();

context.addListener(new LoggerContextListener(){

@Override public void onReset(LoggerContext context){
//context.addListener(this);
}

@Override public boolean isResetResistant(){ return true;}

@Override public void onStart(LoggerContext context){}

@Override public void onStop(LoggerContext context){}

@Override public void onLevelChange(Logger logger, Level level){}
});

context.reset();
Changes include comment for context.addListener(this) and isResetResistant returning true.

There are no two threads trying to act on a shared list, its the same thread trying to modify the list while it is iterated over.

For the current need, I guess making it isResetResistant as true should add this into the listener list when a reset is performed.