break;
            }
        }

        this.canon = new String(out, 0, prefixLen);
        if (prefixLen > 1) {
            prefixLen--;
            final int firstSep = this.canon.indexOf('/', 1);
            if (firstSep < 0) {
                this.share = this.canon.substring(1);
                this.unc = "\\";
            } else if (firstSep == prefixLen) {

            return StringUtil.EMPTY; // empty
        }

        if (url.startsWith("file:////")) {
            final String value = decodeUrlAsName(url.substring(9), true);
            final int pos = value.indexOf('/');
            if (pos > 0) {
                return value.substring(0, pos);
            }
            if (pos == -1) {
                return value;
            }
            return "localhost";

        LaRequestUtil.getOptionalRequest().map(HttpServletRequest::getContextPath).filter(s -> s.length() > 1).ifPresent(s -> sb.append(s));
        sb.append(input);
        if (input.indexOf('?') == -1) {
            try {
                final Long value = resourceHashCache.get(input);
                if (value.longValue() > 0) {
                    sb.append("?t=").append(value.toString());

Let's take this application as example:

{* ../../docs_src/query_params_str_validations/tutorial001_py310.py hl[7] *}

The query parameter `q` is of type `str | None`, that means that it's of type `str` but could also be `None`, and indeed, the default value is `None`, so FastAPI will know it's not required.

/// note

FastAPI will know that the value of `q` is not required because of the default value `= None`.

HSPLkotlin/text/StringsKt__StringsKt;->getLastIndex(Ljava/lang/CharSequence;)I
HSPLkotlin/text/StringsKt__StringsKt;->indexOf$default(Ljava/lang/CharSequence;CIZI)I
HSPLkotlin/text/StringsKt__StringsKt;->indexOf$default(Ljava/lang/CharSequence;Ljava/lang/String;IZI)I
HSPLkotlin/text/StringsKt__StringsKt;->indexOf(Ljava/lang/CharSequence;Ljava/lang/String;IZ)I

![Swagger-Oberfläche](https://fastapi.tiangolo.com/img/index/index-01-swagger-ui-simple.png)

## Alternative API-Dokumentation

                expectedChecksum = expectedChecksum.substring(lastSpacePos + 1);
            } else {
                // remove everything after the first space (if available)
                int spacePos = expectedChecksum.indexOf(' ');

                if (spacePos != -1) {
                    expectedChecksum = expectedChecksum.substring(0, spacePos);
                }
            }

     * @return The file type helper.
     */
    public static FileTypeHelper getFileTypeHelper() {
        return getComponent(FILE_TYPE_HELPER);
    }

    /**
     * Gets the index updater component.
     * @return The index updater.
     */
    public static IndexUpdater getIndexUpdater() {
        return getComponent(INDEX_UPDATER);
    }

    /**
     * Gets the key match helper component.

   * elements directly and null for empty positions, we store indices of the keys in the hash table,
   * and ABSENT for empty positions.  We then look up the keys in alternatingKeysAndValues.
   *
   * (The index actually stored is the index of the key in alternatingKeysAndValues, which is
   * double the index of the entry in entrySet.asList.)
   *

  }

  /**
   * Returns the index in {@code iterable} of the first element that satisfies the provided {@code
   * predicate}, or {@code -1} if the Iterable has no such elements.
   *
   * <p>More formally, returns the lowest index {@code i} such that {@code
   * predicate.apply(Iterables.get(iterable, i))} returns {@code true}, or {@code -1} if there is no
   * such index.
   *
   * @since 2.0
   */