@Override
  public void updateDiskCacheKey(@NonNull MessageDigest messageDigest) {
    messageDigest.update((ID + threshold + quantizationLevels).getBytes(CHARSET));
  }
The threshold at which to apply the edges, default of 0.2.
The levels of quantization for the posterization of colors within the scene,
with a default of 10.0.
transformations/src/main/java/jp/wasabeef/glide/transformations/gpu/ToonFilterTransformation.java