code: public static final void validateKey(String key) throws IllegalArgumentException {
          if (StringUtils.isEmpty(key) || "..".equals(key) || ".".equals(key) || !KEY_PATTERN.matcher(key).matches()) {
              LOG.error("'{}' does not appear to be valid {}", key, KEY_PATTERN);
              throw new IllegalArgumentException(key+" does not appear to be a valid blob key");
          }
      }
docs: Validates key checking for potentially harmful patterns
  @param key Key for the blob.