Unsafe long to int typecast:

public E get(long index) {
    ......
    return curChunk[((int) index)];
    ......
    return spine[j][((int) (index - priorElementCount[j]))];

public E[] asArray(IntFunction<E[]> arrayFactory) {
    // @@@ will fail for size == MAX_VALUE
    E[] result = arrayFactory.apply((int) count());

public T_ARR asPrimitiveArray() {
    // @@@ will fail for size == MAX_VALUE
    T_ARR result = newArray((int) count());

    static class OfInt extends SpinedBuffer.OfPrimitive<Integer, int[], IntConsumer>
        ........
        public int get(long index) {
            int ch = chunkFor(index);
            if (spineIndex == 0 && ch == 0)
                return curChunk[(int) index];
            else
                return spine[ch][(int) (index-priorElementCount[ch])];
        }

Same for:
    static class OfLong
    static class OfDouble