minor change on log debug

Author: Guillaume Arnaud

src/main/java/com/github/brainlag/nsq/lookup/DefaultNSQLookup.java

@@ -33,7 +33,7 @@ public Set<ServerAddress> lookup(String topic) {
                 ObjectMapper mapper = new ObjectMapper();
                 String topicEncoded = URLEncoder.encode(topic, Charsets.UTF_8.name());
                 JsonNode jsonNode = mapper.readTree(new URL(addr + "/lookup?topic=" + topicEncoded));
-                LogManager.getLogger(this).debug("Server connection information: " + jsonNode.toString());
+                LogManager.getLogger(this).debug("Server connection information: {}", jsonNode);
                 JsonNode producers = jsonNode.get("data").get("producers");
                 for (JsonNode node : producers) {
                     String host = node.get("broadcast_address").asText();