}
        return hash;
    }

    /**
     * Encodes a similar document hash using GZIP compression and Base64 encoding.
     * This reduces storage space for hash values while maintaining uniqueness.
     *
     * @param hash the hash string to encode
     * @return the encoded hash string with prefix, or the original hash if encoding fails
     */
    public String encodeSimilarDocHash(final String hash) {