private static int joint(Collection<?> c1, Collection<?> c2) {
    if (c1.size() < c2.size()) {
      return -1;
    } else if (c2.size() < c1.size()) {
      return 1;
    }
    Collection<Object> c3 = new ArrayList<>();
    c3.addAll(c1);
    c3.removeAll(c2);
    if (c3.size() > 0) {
      return -1;
    }
    c3.addAll(c2);
    c3.removeAll(c1);
    if (c3.size() > 0) {
      return 1;
    }
    return 0;
  }
Returns -1 if c1 is missing an element in c2, 1 if c2 is missing an element in c1, or 0 is they
contain the exact same elements.

@throws NullPointerException if either c1 or c2 is null
geode-core/src/integrationTest/java/org/apache/geode/internal/offheap/OffHeapValidationJUnitTest.java