code: public PrivateKey unwrapPrivateKey(String wrappedKey) {
  
          return (PrivateKey) unwrap(wrappedKey, Keys.ASYMMETRIC_ALGORITHM,
                  Cipher.PRIVATE_KEY, WRAP_ALGORITHM_ASYMMETRIC);
      }
docs: Unwraps the given encoded {@link PrivateKey}, using
  WRAP_ALGORITHM_ASYMMETRIC.
  
  @param wrappedKey The wrapped key, base-64 encoded, as returned by
  {@link #wrapPrivateKey(PrivateKey)} .
  @return The unwrapped {@link PrivateKey}.