private void register(Client client) {
        JsonObject clientJson = new JsonObject(Json.encode(client));
        clients.add(clientJson);
        clientMap.put(client, clientJson);
    }
@author Marc Savy {@literal <marc@rhymewithgravy.com>}
gateway/test/src/test/java/io/apiman/gateway/test/junit/vertx3/ApiToFileRegistry.java