question: public Object [ ] toArray ( ) { return Arrays . copyOf ( elementData , size ) ; }
target:  Returns an array containing all of the elements in this list in proper sequence (from first to last element). <p>The returned array will be "safe" in that no references to it are maintained by this list.  (In other words, this method must allocate a new array).  The caller is thus free to modify the returned array. <p>This method acts as bridge between array-based and collection-based APIs.