java.lang.ArrayStoreException异常

Field[] filterCopyFields = Stream.of(appendFields)
     .map(f -> !preFieldNames.contains(f.getName())).toArray(Field[]::new);

    /**
     * Returns an array containing the elements of this stream, using the
     * provided {@code generator} function to allocate the returned array, as
     * well as any additional arrays that might be required for a partitioned
     * execution or for resizing.
     *
     * <p>This is a <a href="package-summary.html#StreamOps" rel="external nofollow" >terminal
     * operation</a>.
     *
     * @apiNote
     * The generator function takes an integer, which is the size of the
     * desired array, and produces an array of the desired size.  This can be
     * concisely expressed with an array constructor reference:
     * <pre>{@code
     *     Person[] men = people.stream()
     *                          .filter(p -> p.getGender() == MALE)
     *                          .toArray(Person[]::new);
     * }</pre>
     *
     * @param <A> the element type of the resulting array
     * @param generator a function which produces a new array of the desired
     *                  type and the provided length
     * @return an array containing the elements in this stream
     * @throws ArrayStoreException if the runtime type of the array returned
     * from the array generator is not a supertype of the runtime type of every
     * element in this stream
     */
    <A> A[] toArray(IntFunction<A[]> generator);

Field[] filterCopyFields = Stream.of(appendFields)
     .filter(f -> !preFieldNames.contains(f.getName())).toArray(Field[]::new);

Object[] toArray(); 
T[] toArray(T[] a);

        List<Integer> list = new ArrayList<Integer>();
        list.add(12);
        list.add(13);
        list.toArray(new Integer[list.size()]);

        List<Integer> list = new ArrayList<Integer>();
        list.add(12);
        list.add(13);
        list.toArray();

public class StingUtilsTest{
    public static void main(String[] args) {
        List<Integer> list = new ArrayList<Integer>();
        list.add(12);
        list.add(13);
        list.toArray(new Long[list.size()]);
    }
}