public Builder addUpgrading(org.bwapi.proxy.messages.GameMessages.UpgradeType value) {
        if (upgradingBuilder_ == null) {
          if (value == null) {
            throw new NullPointerException();
          }
          ensureUpgradingIsMutable();
          upgrading_.add(value);
          onChanged();
        } else {
          upgradingBuilder_.addMessage(value);
        }
        return this;
      }