protected Client getClient(String id) throws IOException {
        GetRequest getRequest = new GetRequest(getIndexPrefixWithJoiner() + EsConstants.INDEX_CLIENTS, id);
        GetResponse result = getClient().get(getRequest, RequestOptions.DEFAULT);

        if (result.isExists()) {
            Client client = JSON_MAPPER.readValue(result.getSourceAsString(), Client.class);
            return client;
        } else {
            return null;
        }
    }
Gets the client synchronously.
@param id the client id
@throws IOException
gateway/engine/es/src/main/java/io/apiman/gateway/engine/es/EsRegistry.java