code: public byte[] getBoosterBytes() {
          final H2ONode boosterNode = getBoosterNode();
          final byte[] boosterBytes;
          if (H2O.SELF.equals(boosterNode)) {
              boosterBytes = XGBoost.getRawArray(XGBoostUpdater.getUpdater(_modelKey).getBooster());
          } else {
              Log.debug("Booster will be retrieved from a remote node, node=" + boosterNode);
              FetchBoosterTask t = new FetchBoosterTask(_modelKey);
              boosterBytes = new RPC<>(boosterNode, t).call().get()._boosterBytes;
          }
          return boosterBytes;
      }
docs: This is called from driver