docs: public boolean isRegisterable(InstanceInfo instanceInfo) {
          DataCenterInfo datacenterInfo = instanceInfo.getDataCenterInfo();
          String serverRegion = clientConfig.getRegion();
          if (AmazonInfo.class.isInstance(datacenterInfo)) {
              AmazonInfo info = AmazonInfo.class.cast(instanceInfo.getDataCenterInfo());
              String availabilityZone = info.get(MetaDataKey.availabilityZone);
              // Can be null for dev environments in non-AWS data center
              if (availabilityZone == null && US_EAST_1.equalsIgnoreCase(serverRegion)) {
                  return true;
              } else if ((availabilityZone != null) && (availabilityZone.contains(serverRegion))) {
                  // If in the same region as server, then consider it registerable
                  return true;
              }
          }
          return true; // Everything non-amazon is registrable.
      }