code: protected int parseZoneId() {
          int result = -1;
          String zoneIdStr = this.request.getHeader(RestMessageHeaders.X_VOLD_ZONE_ID);
          if(zoneIdStr != null) {
              try {
                  int zoneId = Integer.parseInt(zoneIdStr);
                  if(zoneId < 0) {
                      logger.error("ZoneId cannot be negative. Assuming the default zone id.");
                  } else {
                      result = zoneId;
                  }
              } catch(NumberFormatException nfe) {
                  logger.error("Exception when validating request. Incorrect zone id parameter. Cannot parse this to int: "
                                       + zoneIdStr,
                               nfe);
              }
          }
          return result;
      }
docs: Retrieve and validate the zone id value from the REST request.
  "X-VOLD-Zone-Id" is the zone id header.
  
  @return valid zone id or -1 if there is no/invalid zone id