public int getApiPortDynamically(JsonObject apiToFilePushEmulatorConfig) {
        return apiToFilePushEmulatorConfig.getJsonObject("verticles").getJsonObject("api").getInteger("port");
    }
get api port dynamically from configuration
@param apiToFilePushEmulatorConfig configuration
@return api port
gateway/test/src/test/java/io/apiman/gateway/test/junit/vertx3/Vertx3GatewayHelper.java