@Override
    public Optional<Customizer[]> getCustomizers(final String scriptEngineName) {
        if (null == System.getenv(Constants.HADOOP_GREMLIN_LIBS))
            HadoopGraph.LOGGER.warn("Be sure to set the environmental variable: " + Constants.HADOOP_GREMLIN_LIBS);
        else
            HadoopGraph.LOGGER.info(Constants.HADOOP_GREMLIN_LIBS + " is set to: " + System.getenv(Constants.HADOOP_GREMLIN_LIBS));

        return super.getCustomizers(scriptEngineName);
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
hadoop-gremlin/src/main/java/org/apache/tinkerpop/gremlin/hadoop/jsr223/HadoopGremlinPlugin.java