Gets or sets DER-encoded OCSP responses (OCSPResponse, RFC 6960 §4.2.1) to check certificates against, besides those the
signatures and the document security store carry. Empty by default.
public IReadOnlyList<byte[]> OcspResponses { get; set; }
RFC 6960 §4.2; ISO 32000-2 §12.8.3.4.6. A response counts only when the certificate's issuer, or a responder it delegated to (RFC 6960 §4.2.2.2), signed it.