/**
     * Validate string from server response
     *
     * @param str string to validate
     * @param maxLength maximum allowed length
     * @param fieldName field name for error messages
     * @throws SmbException if string is invalid
     */
    public void validateString(String str, int maxLength, String fieldName) throws SmbException {
        totalValidations.incrementAndGet();

        if (str == null) {

                        final long maxLength = contentLengthHelper.getMaxLength(responseData.getMimeType());
                        if (responseData.getContentLength() > maxLength) {
                            throw new MaxLengthExceededException("The content length (" + responseData.getContentLength()
                                    + " byte) is over " + maxLength + " byte. The url is " + filePath);
                        }

                        final long maxLength = contentLengthHelper.getMaxLength(responseData.getMimeType());
                        if (responseData.getContentLength() > maxLength) {
                            throw new MaxLengthExceededException("The content length (" + responseData.getContentLength()
                                    + " byte) is over " + maxLength + " byte. The url is " + filePath);
                        }

        }

        // Always compare full length to prevent timing leaks
        int lengthEqual = (a.length == b.length) ? 1 : 0;
        int maxLength = Math.max(a.length, b.length);

        int result = lengthEqual;
        for (int i = 0; i < maxLength; i++) {
            char charA = (i < a.length) ? a[i] : '\0';
            char charB = (i < b.length) ? b[i] : '\0';
            result &= (charA == charB) ? 1 : 0;

        final int tagLength = getAuthTagLength();
        final byte[] ciphertext = new byte[encrypted.length - tagLength];
        final byte[] authTag = new byte[tagLength];

        // Use constant-time copy operations
        constantTimeCopy(encrypted, 0, ciphertext, 0, ciphertext.length);
        constantTimeCopy(encrypted, ciphertext.length, authTag, 0, tagLength);

    if (string.length() >= minLength) {
      return string;
    }
    StringBuilder sb = new StringBuilder(minLength);
    for (int i = string.length(); i < minLength; i++) {
      sb.append(padChar);
    }
    sb.append(string);
    return sb.toString();
  }

  /**
   * Returns a string, of length at least {@code minLength}, consisting of {@code string} appended

{* ../../docs_src/query_params_str_validations/tutorial002_an_py310.py hl[9] *}

Notice that the default value is still `None`, so the parameter is still optional.

* Update docs for first steps, links and rewording. PR [#1518](https://github.com/tiangolo/fastapi/pull/1518) by [@yankeexe](https://github.com/yankeexe).
* Enable `showCommonExtensions` in Swagger UI to show additional validations like `maxLength`, etc. PR [#1466](https://github.com/tiangolo/fastapi/pull/1466) by [@TiewKH](https://github.com/TiewKH).