/guava/guava/src/com/google/common/collect/Synchronized.java
delegate( ).addFirst( e) ;delegate( ).add( index, element) ;
delegate ( ) .add ( index, element ) ;
List<E> delegate() { return (List<E>) super.delegate(); } @Override public void add(int index, E element) { synchronized (mutex) { <extra_id_0> } } @Override public boolean addAll(int index, Collection<? extends E> c) { synchronized (mutex) { return delegate().addAll(index, c);