does contention in a tthread dump means that the code written by developer is not efficient or can jvm internal threads can also cause contetion?

Does contention only occurs if non daemon threads (application thread ) are trying to acquire the same lock or it can also occurs if daemon threads (jvm internal threads ) causes some issue ?

So, my main question is can daemon threads can cause contention ?

The short answer is yes... WebLogic's threads are all daemon threads.