OSSL_CMP_HDR_get0_recipNonce
nonce = OSSL_CMP_HDR_get0_recipNonce(hdr);
ASN1_OCTET_STRING *OSSL_CMP_HDR_get0_recipNonce(const OSSL_CMP_PKIHEADER *hdr);
header_nonce = OSSL_CMP_HDR_get0_recipNonce(fixture->hdr);