These custom validators are for things that can be checked with **only** the **same data** provided in the request.

///

### Understand that Code { #understand-that-code }

The important point is just using **`AfterValidator` with a function inside `Annotated`**. Feel free to skip this part. 🤸

---

But if you're curious about this specific code example and you're still entertained, here are some extra details.

        return trimParentElementFull(context, root, parentElement, pomMap);
    }

    /**
     * Applies dependency-related inference optimizations.
     * Removes managed dependencies that point to project artifacts.
     */
    private boolean applyDependencyInference(UpgradeContext context, Set<Coordinates> allGAVs, Document pomDocument) {
        boolean hasChanges = false;

       *
       * We store `localFuturesOrNull` inside the listener because `this.futures` might be nulled
       * out by the time the listener runs for the final future -- at which point we need to check
       * all inputs for exceptions *if* we're collecting values. If we're not, then the listener
       * doesn't need access to the futures again, so we can just pass `null`.
       *

  }

  /** Returns a byte string that differs from this one by one bit. */
  private fun ByteString.offByOneBit(): ByteString =
    Buffer()
      .write(this, 0, size - 1)
      .writeByte(this[size - 1].toInt() xor 1)
      .readByteString()

  private fun date(s: String): Date =
    SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ").run {
      timeZone = TimeZone.getTimeZone("GMT")
      parse(s)
    }

If you use a `try` block in a dependency with `yield`, you'll receive any exception that was thrown when using the dependency.

For example, if some code at some point in the middle, in another dependency or in a *path operation*, made a database transaction "rollback" or created any other exception, you would receive the exception in your dependency.

	if c == '.' {
		isFloat = true
		d.scratch.add(c)

		// first char following must be digit
		if c = d.next(); c < '0' || c > '9' {
			return 0, d.mkError(ErrSyntax, "after decimal point in numeric literal")
		}
		d.scratch.add(c)

		for {
			if d.remaining() == 0 {
				return 0, d.mkError(ErrUnexpectedEOF)
			}
			if c = d.next(); c < '0' || c > '9' {
				break
			}

	// For hardrives it is possible to set this to a lower value to avoid any
	// spike in latency. But currently we are simply keeping it optimal for SSDs.

	// bigFileThreshold is the point where we add readahead to put operations.
	bigFileThreshold = 128 * humanize.MiByte

	// XL metadata file carries per object metadata.
	xlStorageFormatFile = "xl.meta"

   * operation is required.
   *
   * This is invoked at most once, even if [Call.cancel] is invoked multiple times. It may be
   * invoked at any point in a call's life, including before [callStart] and after [callEnd].
   */
  open fun canceled(call: Call) {
  }

  /**
   * Invoked when a call fails due to cache rules.

   * next printing line. (Applicable also to display devices.) Where appropriate, this character may
   * have the meaning "New Line" (NL), a format effector which controls the movement of the printing
   * point to the first printing position on the next printing line. Use of this convention requires
   * agreement between sender and recipient of data.
   *
   * @since 8.0
   */
  public static final byte LF = 10;

     * true value. Therefore, we perform at least one Newton iteration to get a guess that's
     * definitely >= floor(sqrt(x)), and then continue the iteration until we reach a fixed point.
     */
    BigInteger sqrt0;
    int log2 = log2(x, FLOOR);
    if (log2 < Double.MAX_EXPONENT) {
      sqrt0 = sqrtApproxWithDoubles(x);
    } else {