public static BigInteger fromUnsignedBigEndianBytes(byte[] bytes) {
    return new BigInteger(1, bytes);
  }
Parses a {@link BigInteger} from a byte array using unsigned big-endian encoding.

<p>See also <a href="https://www.rfc-editor.org/rfc/rfc8017#section-4.2">RFC 8017, Sec. 4.2</a>
java_src/src/main/java/com/google/crypto/tink/internal/BigIntegerEncoding.java