@Override
    public void startStream() {
        for (final DestinationProvider destinationProvider : destinationProviders) {
            destinationProvider.startStream();
        }
        super.startStream();
    }
Called by the pipeline when processing of a file is complete.

@see stroom.pipeline.filter.AbstractXMLFilter#endProcessing()
stroom-pipeline/src/main/java/stroom/pipeline/writer/AbstractWriter.java