@Override
    public void close() throws IOException {
        closed = true;
        try {
            data.close();
        } finally {
            try {
                indexInputStream.close();
            } finally {
                super.close();
            }
        }
    }
Wrapper for a nested input stream.
<p>
You must call getNextEntry and closeEntry like the ZIP API.
stroom-data/stroom-data-store-impl-fs/src/main/java/stroom/data/store/impl/fs/RANestedInputStream.java