@SuppressWarnings("NullableProblems")
    @Override
    public void write(byte[] b, int off, int len) throws IOException {
        segmentOutputStream.write(b, off, len);
    }
Class used to write multiple streams to a single stream separated by segments
by a segment marker (boundary).
stroom-data/stroom-data-store-impl-fs/src/main/java/stroom/data/store/impl/fs/RANestedOutputStream.java