code: public static URI ocspUri(X509Certificate certificate) throws IOException {
          byte[] value = certificate.getExtensionValue(Extension.authorityInfoAccess.getId());
          if (value == null) {
              return null;
          }
  
          ASN1Primitive authorityInfoAccess = X509ExtensionUtil.fromExtensionValue(value);
          if (!(authorityInfoAccess instanceof DLSequence)) {
              return null;
          }
  
          DLSequence aiaSequence = (DLSequence) authorityInfoAccess;
          DERTaggedObject taggedObject = findObject(aiaSequence, OCSP_RESPONDER_OID, DERTaggedObject.class);
          if (taggedObject == null) {
              return null;
          }
  
          if (taggedObject.getTagNo() != BERTags.OBJECT_IDENTIFIER) {
              return null;
          }
  
          byte[] encoded = taggedObject.getEncoded();
          int length = (int) encoded[1] & 0xFF;
          String uri = new String(encoded, 2, length, CharsetUtil.UTF_8);
          return URI.create(uri);
      }
docs: Returns the OCSP responder {@link URI} or {@code null} if it doesn't have one.