void forEachRangeValueEntry(final Consumer<Entry<RangeStoreKey, StagingValue>> entryStreamConsumer) {
        stagingLmdbEnv.doWithReadTxn(readTxn -> {
            rangeValueStagingDb.forEachEntry(readTxn, KeyRange.all(), stagingEntry -> {
                final RangeStoreKey key = stagingEntry.getKey().getKey();
                final StagingValue stagingValue = stagingEntry.getValue();
                entryStreamConsumer.accept(Map.entry(key, stagingValue));
            });
        });
    }
Loop over all entries in the range/value store. There may be multiple values for the same range.
Looping is done in key order, NOT in the oder they were originally put.
REMEMBER, the entries contain buffers used by LMDB so if you want to do anything with the entries
outside of the consumer you need to copy!
stroom-pipeline/src/main/java/stroom/pipeline/refdata/store/offheapstore/OffHeapStagingStore.java