@Override
    public int hashCode() {
        int hashCode = super.hashCode() ^ Objects.hashCode(this.serviceName);
        if (!staticParams.get().isEmpty())
            hashCode ^= staticParams.get().hashCode();
        if (mapTraversal != null)
            hashCode ^= mapTraversal.hashCode();
        if (!parameters.isEmpty())
            hashCode ^= parameters.hashCode();
        return hashCode;
    }
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