*
     * @return the hash algorithm
     */
    public int getSelectedHashAlgorithm() {
        return selectedHashAlgorithm;
    }

    /**
     * Calculates hash according to SMB 3.1.1 preauth integrity specification.
     *
     * @param previousHash the previous hash in the chain
     * @param messageData the message data to hash
     * @param hashAlgorithm the hash algorithm to use

    return (elements.length == 0)
        ? ImmutableList.<E>of()
        : ImmutableList.<E>construct(elements.clone());
  }

  /**
   * Returns an immutable list containing the given elements, sorted according to their natural
   * order. The sorting algorithm used is stable, so elements that compare as equal will stay in the
   * order in which they appear in the input.
   *

    /**
     * Encodes a URL by encoding non-URL-safe characters.
     * Uses the request's character encoding if available, otherwise defaults to UTF-8.
     * Only encodes characters that are not considered URL-safe according to CharUtil.
     *
     * @param url the URL to encode
     * @return the encoded URL with non-URL-safe characters properly encoded
     */
    public static String encodeUrl(final String url) {

   * Creates a {@code PriorityBlockingQueue} containing the given elements.
   *
   * <p><b>Note:</b> If the specified iterable is a {@code SortedSet} or a {@code PriorityQueue},
   * this priority queue will be ordered according to the same ordering.
   *
   * @since 11.0 (but the bound of {@code E} was changed from {@code Object} to {@code Comparable}
   *     in 15.0)
   */

        return Double.longBitsToDouble(dec_uint64be(src, si));
    }

    /* Encode times
     */

    /**
     * Encodes a Date value according to the specified time encoding type.
     *
     * @param date the Date to encode
     * @param dst the destination byte array
     * @param di the starting index in the destination array

    return ensureInUnitRange(sumOfProductsOfDeltas / Math.sqrt(productOfSumsOfSquaresOfDeltas));
  }

  /**
   * Returns a linear transformation giving the best fit to the data according to <a
   * href="http://mathworld.wolfram.com/LeastSquaresFitting.html">Ordinary Least Squares linear
   * regression</a> of {@code y} as a function of {@code x}. The count must be greater than one, and

      <fields>
        <field>
          <name>profiles</name>
          <version>1.0.0</version>
          <description><![CDATA[
            Configuration of build profiles for adjusting the build
            according to environmental parameters
          ]]></description>
          <association>
            <type>Profile</type>
            <multiplicity>*</multiplicity>
          </association>
        </field>
        <field>

 * multiple variants of ASN.1, including:
 *
 *  * DER: Distinguished Encoding Rules. This further constrains ASN.1 for deterministic encoding.
 *  * BER: Basic Encoding Rules.
 *
 * This class was implemented according to the [X.690 spec][[x690]], and under the advice of
 * [Lets Encrypt's ASN.1 and DER][asn1_and_der] guide.
 *
 * [x690]: https://www.itu.int/rec/T-REC-X.690

 *
 * The end of the range is not encoded, but can be inferred by looking at the start of the range
 * that follows.
 *
 * b1
 * --
 *
 * This is either a mapping decision or the length of the mapped output, according to this table:
 *
 * ```
 *  0..63 : Length of the UTF-16 sequence that this range maps to. The offset is b2b3.
 * 64..79 : Offset by a fixed negative offset. The bottom 4 bits of b1 are the top 4 bits of the offset.

httpx.post(callback_url, json={"description": "Invoice paid", "paid": True})
```

But possibly the most important part of the callback is making sure that your API user (the external developer) implements the *external API* correctly, according to the data that *your API* is going to send in the request body of the callback, etc.

So, what we will do next is add the code to document how that *external API* should look like to receive the callback from *your API*.