cglib/src/main/java/net/sf/cglib/util/ParallelSorter.java
public void mergeSort(int index, int lo, int hi, Comparator cmp) {
        chooseComparer(index, cmp);
        super.mergeSort(lo, hi - 1);
    }
public void mergeSort(int index, int lo, int hi, Comparator cmp) {
        chooseComparer(index, cmp);
        super.mergeSort(lo, hi - 1);
    }
Sort the arrays using an in-place merge sort.
@param index array (column) to sort by
@param lo starting array index (row), inclusive
@param hi ending array index (row), exclusive
@param cmp Comparator to use if the specified column is non-primitive