code: private static String normalisedScheme(char[] scheme) {
          if (scheme == null) {
              return "";
          }
          return new String(scheme).toLowerCase(Locale.ROOT);
      }
docs: Returns the normalised form of the given {@code scheme}.
  <p>
  The normalisation process consists in converting the scheme to lowercase, if {@code null} it is returned an empty
  {@code String}.
  
  @param scheme the scheme that will be normalised
  @return a {@code String} with the host scheme, never {@code null}
  @see URI#getRawScheme()