docs: private boolean isValidKeyUsage(final X509Certificate certificate) {
          LOGGER.debug("Checking certificate keyUsage extension");
          val keyUsage = certificate.getKeyUsage();
          if (keyUsage == null) {
              LOGGER.warn("Configuration specifies checkKeyUsage but keyUsage extension not found in certificate.");
              return !this.requireKeyUsage;
          }
  
          val func = FunctionUtils.doIf(c -> isCritical(certificate, KEY_USAGE_OID) || requireKeyUsage,
              t -> {
                  LOGGER.debug("KeyUsage extension is marked critical or required by configuration.");
                  return keyUsage[0];
              },
              f -> {
                  LOGGER.debug("KeyUsage digitalSignature=%s, Returning true since keyUsage validation not required by configuration.");
                  return Boolean.TRUE;
              });
          return func.apply(certificate);
      }