@Override
    public Configuration getConfiguration() {
        final Configuration conf = super.getConfiguration();
        conf.setProperty(ID_PROPERTY_KEY, this.idPropertyKey);
        // The idMaker is not serializable. The default idMaker is excluded from the configuration to allow for remote
        // serialization. Custom idMakers are only supported in the config for embedded usages.
        if (!idMaker.equals(Builder.DEFAULT_ID_MAKER)) {
            conf.setProperty(ID_MAKER, this.idMaker);
        }
        return conf;
    }
This key within which to hold the user-specified identifier.  This field should be indexed by the
underlying graph.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/strategy/decoration/ElementIdStrategy.java