Casting variables - java.lang.ClassCastException [on ArrayCollection example]

Question

I'm trying to implement Collection interface for study purpose. My add() and toArray() method looks like:

public class ArrayCollection<T> implements Collection<T> {

private T[] m = (T[])new Object[10];

private int size = 0;

@Override
public boolean add(final T t) {        
    m[size++] = t;
    return true;
}

@Override
public Object[] toArray() {
    T[] array = (T[]) new Object[size()];
    int i = 0;
    for (T item : ArrayCollection.this) {
        array[i++] = item;
    }
    return array;
}

But when I perform testing:

@Test
public void testToArray() throws Exception {
    final Collection<Integer> testInstance = new ArrayCollection<>();
    testInstance.add(1);
    testInstance.add(2);
    testInstance.add(3);

    final Integer[] result = testInstance.toArray();

    assertEquals((Integer)1, result[0]);
    assertEquals((Integer)2, result[1]);
    assertEquals((Integer)3, result[2]);
    assertEquals(3, result.length);
}

I get error:

ArrayCollectionTest.java:32: error: incompatible types: Object[] cannot be converted to Integer[]
final Integer[] result = testInstance.toArray();

I completelly don't uderstand how to fix this problem and what I'm doing wrong.