@Override
  public int available() throws IOException {
    // Return estimate of the bytes remaining, bounded by max int value.
    return (int) Math.min(streamSize - position, Integer.MAX_VALUE);
  }
Returns 'size' number of zero bytes when read from.
@param size The number of zero bytes to be returned.
@throws IOException
ambry-utils/src/main/java/com/github/ambry/utils/ZeroBytesInputStream.java