static int hash(int h) {
    // This function ensures that hashCodes that differ only by
    // constant multiples at each bit position have a bounded
    // number of collisions (approximately 8 at default load factor).
    h ^= (h >>> 20) ^ (h >>> 12);
    return h ^ (h >>> 7) ^ (h >>> 4);
  }
Applies a supplemental hash function to a given hashCode, which defends against poor quality
hash functions. This is critical because IntHashMap uses power-of-two length hash tables, that
otherwise encounter collisions for hashCodes that do not differ in lower bits. Note: Null keys
always map to hash 0, thus index 0.
geode-core/src/main/java/org/apache/geode/cache/query/internal/ObjectIntHashMap.java