protected Map<String, String> getConfig(JsonObject obj, String prefix) {
        // First, check whether there's something interesting in System properties.
        Map<String, String> mfp = getConfigMapFromProperties("apiman-gateway." + prefix);

        if (mfp != null && !mfp.isEmpty()) { // TODO
            return mfp;
        }
        return toFlatStringMap(obj.getJsonObject(prefix, new JsonObject()).getJsonObject(GATEWAY_CONFIG));
    }
@see io.apiman.gateway.engine.IEngineConfig#getGatewayInitializers(io.apiman.gateway.engine.IPluginRegistry)
gateway/platforms/vertx3/vertx3/src/main/java/io/apiman/gateway/platforms/vertx3/common/config/VertxEngineConfig.java