@Override
    public void loadState(final Graph graph, final Configuration configuration) {
        this.memoryKey = configuration.getString(CLUSTER_POPULATION_MEMORY_KEY, DEFAULT_MEMORY_KEY);
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/computer/clustering/peerpressure/ClusterPopulationMapReduce.java