code: private void writeItem(FakeEncodedItem item) {
        int endPosition = dataPosition + item.sizeBytes;
        if (endPosition > data.length) {
          // Parcel grows by 3/2 of the new size.
          setDataCapacityAtLeast(endPosition * 3 / 2);
        }
        if (endPosition > dataSize) {
          failNextReadIfPastEnd = true;
          dataSize = endPosition;
        }
        Arrays.fill(data, dataPosition, endPosition, item);
        dataPosition = endPosition;
      }
docs: Writes an encoded item directly, bypassing alignment, and possibly repeating an item.