code: public JwtBuilder signWith(String algorithm, Key key) throws KeyException {
          builder = builder.signWith(algorithm, key);
          return this;
      }
docs: Signing key and algorithm information.
  
  @param algorithm
  This String value represents the signing algorithm. This information will be used
  to sign the {@code JwtToken}
  @param key
  The private key {@code Key} to use for signing JWTs.
  @return {@code JwtBuilder} object
  @throws KeyException
  Thrown if the key is {@code null} or if algorithm is {@code null} or empty