KafkaSuscriber: log incoming messages

Log as INFO level all incoming messages with header and body.
This helps troubleshooting common problems and check that the
new Kafka-based streaming reindexing propagation actually works
as expected.

Change-Id: I9d64453fe6a40aefc178c3462c5ecc02a0d75fff

src/main/java/com/googlesource/gerrit/plugins/multisite/kafka/consumer/BrokerReadEvent.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/multisite/kafka/consumer/BrokerReadEvent.java b/src/main/java/com/googlesource/gerrit/plugins/multisite/kafka/consumer/BrokerReadEvent.java
index c5e083c..191bd39 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/multisite/kafka/consumer/BrokerReadEvent.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/multisite/kafka/consumer/BrokerReadEvent.java
@@ -66,6 +66,12 @@
     public Long getEventCreatedOn() {
       return eventCreatedOn;
     }
+
+    @Override
+    public String toString() {
+      return String.format(
+          "ts=%s, id=%s, type=%s, source=%s", eventCreatedOn, eventId, eventType, sourceInstanceId);
+    }
   }
 
   public BrokerReadEvent(KafkaEventHeader header, JsonObject body) {

src/main/java/com/googlesource/gerrit/plugins/multisite/kafka/consumer/KafkaSubcriber.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/multisite/kafka/consumer/KafkaSubcriber.java b/src/main/java/com/googlesource/gerrit/plugins/multisite/kafka/consumer/KafkaSubcriber.java
index 2e606ad..d7f688c 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/multisite/kafka/consumer/KafkaSubcriber.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/multisite/kafka/consumer/KafkaSubcriber.java
@@ -89,6 +89,7 @@
             event.toString(), instanceId.toString());
       } else {
         try {
+          logger.atInfo().log("Header[%s] Body[%s]", event.getHeader(), event.getBody());
           eventRouter.route(event.getEventBody(gsonProvider));
         } catch (IOException e) {
           logger.atSevere().log(