Fix issue with kafka subscribers properties

KafkaProperties class is formatting configuration parameters from camel
case to separeted by dot. This formatting is required by kafka producer
and consumer. KafkaSubscriberProperties must follow the same pattern.

Bug: Issue 12109
Change-Id: Iede3c9e35eb405ccb2ec9ade45aede811e83131a
diff --git a/src/main/java/com/googlesource/gerrit/plugins/kafka/config/KafkaSubscriberProperties.java b/src/main/java/com/googlesource/gerrit/plugins/kafka/config/KafkaSubscriberProperties.java
index b50053f..c3fd917 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/kafka/config/KafkaSubscriberProperties.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/kafka/config/KafkaSubscriberProperties.java
@@ -33,10 +33,10 @@
     super(configFactory, pluginName);
 
     this.pollingInterval =
-        Integer.parseInt(getProperty("pollingIntervalMs", DEFAULT_POLLING_INTERVAL_MS));
-    this.groupId = getProperty("groupId");
+        Integer.parseInt(getProperty("polling.interval.ms", DEFAULT_POLLING_INTERVAL_MS));
+    this.groupId = getProperty("group.id");
     this.numberOfSubscribers =
-        Integer.parseInt(getProperty("numberOfSubscribers", DEFAULT_NUMBER_OF_SUBSCRIBERS));
+        Integer.parseInt(getProperty("number.of.subscribers", DEFAULT_NUMBER_OF_SUBSCRIBERS));
   }
 
   public Integer getPollingInterval() {