private void endGzipBlock() throws IOException {
        blockCount++;

        currentStreamBuffer.flush();
        currentStreamGzip.flush();
        currentStreamGzip.finish();

        // Block Compressed size is size of stream less magic marker less block
        // size header (2 longs)
        long rawBlockSize = mainBuffer.size() - BlockGZIPConstants.LONG_BYTES - BlockGZIPConstants.LONG_BYTES;
        mainBuffer.overwriteLongAtOffset(BlockGZIPConstants.LONG_BYTES, rawBlockSize);

        flushMainBuffer();

        currentStreamBuffer = null;
        currentStreamGzip = null;
    }
Start a new burst of GZIP Block Content (with a marker).
stroom-data/stroom-data-store-impl-fs/src/main/java/stroom/data/store/impl/fs/BlockGZIPOutputFile.java