What is the left shift point for zero?

Question

I am looking at the verboden sun.misc.Unsafe code and I see quite a few examples, for example

//Gives an absolute address given the base address & an offset i
private long ix(int i) {
    return address + (i << 0);
}

At first glance, this does not mean and should not do anything simple address + i, but nevertheless, an idiom appears everywhere. What's going on here?