private static ArrayNode addStyler(final ArrayNode inputNode, final GoogleMapsThemeOption option, final boolean on) {
        ArrayNode node = inputNode;
        if (node == null) {
            node = JsonUtils.createArrayNode();
        }
        node.add(createVisibilityOnStylerForFeatureType(option.getFeatureName(), on));
        return node;
    }
apply theme options to given GM as currently stored in settings
main/src/main/java/cgeo/geocaching/unifiedmap/googlemaps/GoogleMapsThemeHelper.java