@SuppressWarnings("NullableProblems")
    @Override
    public int read(final byte[] b) throws IOException {
        int rtn = super.read(b);
        if (rtn != -1) {
            // Accumulate the bytes read
            streamPosition += rtn;
        }
        return rtn;
    }
Point at a new input stream and reset our markers. Used to avoid
allocating new buffers.

@param newIn new stream to read
stroom-data/stroom-data-store-impl-fs/src/main/java/stroom/data/store/impl/fs/BlockBufferedInputStream.java