private static @NotNull <K> Hash.Strategy<K> getFastutilHashingStrategy(@NotNull HashingStrategy<K> strategy) {
    return new Hash.Strategy<K>() {
      @Override
      public int hashCode(@Nullable K o) {
        return o == null ? 0 : strategy.hashCode(o);
      }

      @Override
      public boolean equals(@Nullable K a, @Nullable K b) {
        return a == b || (a != null && b != null && strategy.equals(a, b));
      }
    };
  }
private static @NotNull <K> Hash.Strategy<K> getFastutilHashingStrategy(@NotNull HashingStrategy<K> strategy)