@Test
    void can_extract_public_key_from_x25519_private_key() {
        var priv = xecPrivFromHex("77076d0a7318a57d3c16c17251b26645df4c2f87ebc0992ab177fba51db92c2a");
        var expectedPubHex = "8520f0098930a754748b7ddcb43ef75a0dbf3a0d26381af4eba4a98eaa9b4e6a";
        var pub = KeyUtils.extractX25519PublicKey(priv);
        assertEquals(expectedPubHex, xecHexFromPub(pub));

        priv = xecPrivFromHex("5dab087e624a8a4b79e17f8b83800ee66f3bb1292618b6fd1c2f8b27ff88e0eb");
        expectedPubHex = "de9edb7d7b7dc1b4d35b61c2ece435373f8343c85b78674dadfc7e146f882b4f";
        pub = KeyUtils.extractX25519PublicKey(priv);
        assertEquals(expectedPubHex, xecHexFromPub(pub));
    }
RFC 7748 Section 6.1, Curve25519 Diffie-Hellman test vector
security-utils/src/test/java/com/yahoo/security/KeyUtilsTest.java