Fix warnings about redundant type arguments

Change-Id: I6e891798549e2eaf4125ddbcd19057f0c1fb45a4

src/main/java/com/googlesource/gerrit/plugins/validators/CommitMessageLengthValidation.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/validators/CommitMessageLengthValidation.java b/src/main/java/com/googlesource/gerrit/plugins/validators/CommitMessageLengthValidation.java
index 2e06a7d..d5d0f4c 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/validators/CommitMessageLengthValidation.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/validators/CommitMessageLengthValidation.java
@@ -83,7 +83,7 @@
       throws CommitValidationException {
     final RevCommit commit = receiveEvent.commit;
     final AbbreviatedObjectId id = commit.abbreviate(7);
-    List<CommitValidationMessage> messages = new ArrayList<CommitValidationMessage>();
+    List<CommitValidationMessage> messages = new ArrayList<>();
 
     if (this.maxSubjectLength < commit.getShortMessage().length()) {
       onLineTooLong(id, messages,