protected List<String> getListStringFromConfig(final String token, final Map<String, Object> config) {
        final List<String> classNameList;
        try {
            classNameList = (List<String>) config.getOrDefault(token, Collections.emptyList());
        } catch (Exception ex) {
            throw new IllegalStateException(String.format("Invalid configuration value of [%s] for [%s] setting on %s serialization configuration",
                    config.getOrDefault(token, ""), token, this.getClass().getName()), ex);
        }

        return classNameList;
    }
Gets a {@link List} of strings from the configuration object.
gremlin-util/src/main/java/org/apache/tinkerpop/gremlin/util/ser/AbstractMessageSerializer.java