If we add lig4j jar after tika-app jar in classpath it does not resolve LoggingEvent class getTimeStamp() method

I am trying to create a custom log4j appender class where I have used tika-app-1.2.jar and log4j-1.2.17. If I use getTimeStamp() method of LoggingEvent class in custom appender and noticed that if I have tika-app jar above log4j jar in classpath it gives me error on getTimeStamp() where as if I move down the tika-app jar below the log4j jar in class path it works fine.