Change logging message and level for closed connection.

Change-Id: I9471a1ed467c350f2416b6acec171d1546e57073
diff --git a/src/main/java/com/googlesource/gerrit/plugins/rabbitmq/session/type/AMQPSession.java b/src/main/java/com/googlesource/gerrit/plugins/rabbitmq/session/type/AMQPSession.java
index 437713e..27acc6f 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/rabbitmq/session/type/AMQPSession.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/rabbitmq/session/type/AMQPSession.java
@@ -69,9 +69,9 @@
           } else if (clazz == Connection.class) {
             Connection conn = Connection.class.cast(obj);
             if (cause.isInitiatedByApplication()) {
-              LOGGER.info(MSG("Connection closed."));
+              LOGGER.info(MSG("Connection closed by application."));
             } else {
-              LOGGER.info(MSG("Connection suddenly closed."));
+              LOGGER.warn(MSG("Connection closed. Cause: {}"), cause.getMessage());
             }
             if (conn.equals(AMQPSession.this.connection)) {
               AMQPSession.this.connection = null;