code: public static String toStringUnsignedInt(byte[] key) {
          StringBuilder result = new StringBuilder();
          for (int i = 0; i < key.length; i++) {
              result.append(key[i] & 0xFF);
              result.append(' ');
          }
          return result.toString();
      }
docs: Generates a string representation of the given key
  
  @param key
  @return the String representation of the given key