@Override
    public Parameters getParameters() {
        return this.parameters;
    }
Reference implementation for service calls via the {@link ServiceRegistry} and {@link Service} APIs. This step
can be used to start a traversal or it can be used mid-traversal with one at a time or barrier execution.

@author Mike Personick (http://github.com/mikepersonick)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/CallStep.java