Open review DB in try-with-resource

Change-Id: I2f545840a96ad6c0fd91adbc44f84af775008ab6

src/main/java/com/googlesource/gerrit/plugins/singleusergroup/SingleUserGroup.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/singleusergroup/SingleUserGroup.java b/src/main/java/com/googlesource/gerrit/plugins/singleusergroup/SingleUserGroup.java
index 9d72b1b..d1e3b06 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/singleusergroup/SingleUserGroup.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/singleusergroup/SingleUserGroup.java
@@ -166,8 +166,7 @@
       List<GroupReference> matches = Lists.newArrayListWithCapacity(MAX);
       String a = name;
       String b = end(a);
-      ReviewDb db = schemaFactory.open();
-      try {
+      try (ReviewDb db = schemaFactory.open()) {
         if (name.matches(ACCOUNT_ID_PATTERN)) {
           Account.Id id = new Account.Id(Integer.parseInt(name));
           if (db.accounts().get(id) != null) {
@@ -211,8 +210,6 @@
         }
 
         return matches;
-      } finally {
-        db.close();
       }
     } catch (OrmException err) {
       log.warn("Cannot suggest users", err);