private String getPipelineVersion(final PipelineReference pipelineReference) {
        return refDataLoaderHolder.getPipelineVersion(pipelineReference, pipelineStore);
    }
Get an event list from a stream that is a nested child of the current
stream context and is therefore not effective time sensitive.
i.e. a context stream attached to this stream and contains data applicable
to this stream only.
stroom-pipeline/src/main/java/stroom/pipeline/refdata/ReferenceData.java