code: @Nonnegative
    public static int getUTF8ByteCount (@Nullable final String s)
    {
      return s == null ? 0 : getUTF8ByteCount (s.toCharArray ());
    }
docs: Get the number of bytes necessary to represent the passed string as an
  UTF-8 string.
  
  @param s
  The string to count the length. May be <code>null</code> or empty.
  @return A non-negative value.