[logback-user] AbstractMethodError in LogbackMDCAdapter

Hi all, I am using logback 0.9.9 with activemq 5.5.1.  Right after startup, the application always encounters an AbstractMethodException in LogbackMDCAdapter, which is firstly triggered by  PooledTaskRunner (line 45).  A snippet is provided as: public static void main(String[] args) { MDCAdapter l = StaticMDCBinder.SINGLETON.getMDCA(); Map m = l.getCopyOfContextMap();  // <-- got excpetion System.out.println("np error"); // never come to this line } Seems that the concrete class LogbackMDCAdapter implements MDCAdapter without implementing the defined method getCopyOfContextMap().   Any clues? Thanks, Hei