@Override
    public List<GremlinScriptEngineFactory> getEngineFactories() {
        final List<GremlinScriptEngineFactory> res = new ArrayList<>(engineSpis.size());
        res.addAll(engineSpis.stream().collect(Collectors.toList()));
        return Collections.unmodifiableList(res);
    }
Returns a list whose elements are instances of all the {@link GremlinScriptEngineFactory} classes
found by the discovery mechanism.

@return List of all discovered {@link GremlinScriptEngineFactory} objects.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/jsr223/DefaultGremlinScriptEngineManager.java