for (int i = 0; i < n; i++) {
        // requireNonNull is safe because we ensure that the first n elements have been populated.
        Object e = requireNonNull(elements[i]);
        int j0 = Hashing.smear(e.hashCode());
        for (int j = j0; ; j++) {
          int index = j & mask;
          if (hashTable[index] == null) {
            hashTable[index] = e;
            break;
          }
        }
      }