public Map getMergedParams() {
        if (mapTraversal == null && parameters.isEmpty()) {
            // static params only
            return Collections.unmodifiableMap(this.staticParams.get());
        }

        return getMergedParams(new DummyTraverser(this.traversal.getTraverserGenerator()));
    }
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