Remove double brace initialization

The build of this module was failing due to not being compliant with the
errorprone setting, in particular with double brace initalization [1].
This can also be seen on the CI [2].

[1]: https://errorprone.info/bugpattern/DoubleBraceInitialization
[2]: https://gerrit-ci.gerritforge.com/view/Plugins-stable-3.7/job/module-index-elasticsearch-bazel-stable-3.7/

Bug: Issue 291102095
Release-Notes: skip
Change-Id: Id07f8688a4e68c0998dcf57c77f035b1e0ebc11d

src/main/java/com/google/gerrit/elasticsearch/ElasticSetting.java

diff --git a/src/main/java/com/google/gerrit/elasticsearch/ElasticSetting.java b/src/main/java/com/google/gerrit/elasticsearch/ElasticSetting.java
index c054da6..2fcfc90 100644
--- a/src/main/java/com/google/gerrit/elasticsearch/ElasticSetting.java
+++ b/src/main/java/com/google/gerrit/elasticsearch/ElasticSetting.java
@@ -16,7 +16,6 @@
 
 import com.google.common.collect.ImmutableMap;
 import com.google.gson.annotations.SerializedName;
-import java.util.HashMap;
 import java.util.Map;
 
 class ElasticSetting {
@@ -60,12 +59,7 @@
 
       FieldProperties analyzer = new FieldProperties();
       analyzer.customWithCharFilter = customAnalyzer;
-      analyzer.keywordTokenizer =
-          new HashMap<>() {
-            {
-              put("tokenizer", "keyword");
-            }
-          };
+      analyzer.keywordTokenizer = ImmutableMap.of("tokenizer", "keyword");
       fields.put("analyzer", analyzer);
       return this;
     }