// OCSP responses found as signed ID_ADBE_REVOCATION attribute
 public Set<OCSPResponse> getSignedOCSPResponses() {
   try {
     AttributeTable table = firstSignerInfo.getSignedAttributes();
     return SignedAttributesHelper.getSignedOCSPResponses(table);
   } catch (Exception e) {
     ExceptionHandlerTyped.<SPISignatureException>handle(SPISignatureException.class, e);
   }
   return null;
 }