@Override
        public Key createKey(final Key parentKey,
                             final StoredValues storedValues,
                             final ByteBuffer keyBuffer) {
            final int parentDepth = parentKey.getDepth();
            if (parentDepth >= 0) {
                throw new RuntimeException("Unexpected parent key");
            }
            final long timeMs = storedValueKeyFactory.getTimeMs(storedValues);
            final Val[] groupValues = storedValueKeyFactory.getGroupValues(parentDepth + 1, storedValues);
            return parentKey.resolve(timeMs, groupValues);
        }
Creates a flat time based group key. <TIME_MS><GROUP_HASH>
stroom-query/stroom-query-common/src/main/java/stroom/query/common/v2/LmdbRowKeyFactoryFactory.java