Remove redundant specification of type arguments

Type arguments are not necessary in Java 7.

Change-Id: Id46acd4e50fef7f7bf05210592b71063897115b8
diff --git a/src/main/java/com/googlesource/gerrit/plugins/rabbitmq/Properties.java b/src/main/java/com/googlesource/gerrit/plugins/rabbitmq/Properties.java
index 8c60968..0123fc5 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/rabbitmq/Properties.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/rabbitmq/Properties.java
@@ -125,7 +125,7 @@
   }
 
   private AMQP.BasicProperties generateBasicProperties() {
-    Map<String, Object> headers = new HashMap<String, Object>();
+    Map<String, Object> headers = new HashMap<>();
     headers.put(Keys.GERRIT_NAME.key, getString(Keys.GERRIT_NAME));
     headers.put(Keys.GERRIT_HOSTNAME.key, getString(Keys.GERRIT_HOSTNAME));
     headers.put(Keys.GERRIT_SCHEME.key, getString(Keys.GERRIT_SCHEME));