docs: public Coin getValue(TransactionBag wallet) throws ScriptException {
          // FIXME: TEMP PERF HACK FOR ANDROID - this crap can go away once we have a real payments API.
          boolean isAndroid = Utils.isAndroidRuntime();
          if (isAndroid && cachedValue != null && cachedForBag == wallet)
              return cachedValue;
          Coin result = getValueSentToMe(wallet).subtract(getValueSentFromMe(wallet));
          if (isAndroid) {
              cachedValue = result;
              cachedForBag = wallet;
          }
          return result;
      }