public void engineInitSender(PublicKey recipientKey, byte[] info, PrivateKey senderKey,
                byte[] psk, byte[] psk_id) throws InvalidKeyException {
            realSpi.engineInitSender(recipientKey, info, senderKey, psk, psk_id);
        }
Tests for DuckTypedHpkeSpiTest. Essentially the same as the tests for HpkeContext but
with a "foreign" HPKE Provider inserted ahead of Conscrypt. That is, one which returns
SPI instances with all the correct methods but which don't inherit directly from "our"
HpkeSpi.
common/src/test/java/org/conscrypt/DuckTypedHpkeSpiTest.java