if (bucketHead == null) {
        boolean canReuseEntry =
            entry instanceof ImmutableEntry && !(entry instanceof NonTerminalEntry);
        newEntry =
            canReuseEntry ? (ImmutableEntry<E>) entry : new ImmutableEntry<E>(element, count);
      } else {
        newEntry = new NonTerminalEntry<>(element, count, bucketHead);
      }
      hashCode += hash ^ count;
      entryArray[index++] = newEntry;