@Override
    public String getId() {
        if (id == null) {
            id = gifDecoder.getId() + bitmapDecoder.getId();
        }
        return id;
    }
An {@link ResourceDecoder} that can decode either an {@link Bitmap} or an {@link GifDrawable}
from an {@link InputStream} or a {@link android.os.ParcelFileDescriptor ParcelFileDescriptor}.
core/src/main/java/com/bumptech/glide/load/resource/gifbitmap/GifBitmapWrapperResourceDecoder.java