// These contain bytes not in the decodabet.
    assertFailsToDecode(base64(), "A\u007f", "Unrecognized character: 0x7f");
    assertFailsToDecode(base64(), "Wf2!", "Unrecognized character: !");
    // This sentence just isn't base64() encoded.
    assertFailsToDecode(base64(), "let's not talk of love or chains!");
    // A 4n+1 length string is never legal base64().
    assertFailsToDecode(base64(), "12345", "Invalid input length 5");

      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works

      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works

      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works

      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works

      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works

      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works

      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works

   * Returns a {@code HostSpecifier} built from the provided {@code specifier}, which is already
   * known to be valid. If the {@code specifier} might be invalid, use {@link #from(String)}
   * instead.
   *
   * <p>The specifier must be in one of these formats:
   *
   * <ul>
   *   <li>A domain name, like {@code google.com}
   *   <li>A IPv4 address string, like {@code 127.0.0.1}

    }

    /**
     * Adds a {@link TraverserFactory}.
     *
     * @param protocol
     *            The URL protocol. Must not be {@literal null} or empty.
     * @param factory
     *            The {@link Traverser} factory for the protocol. Must not be {@literal null}.
     */
    public static void addTraverserFactory(final String protocol, final TraverserFactory factory) {