Remove unused imports in Helper.java

Change-Id: I41fed3e32aea6bbd3e766c788273a745cee45d89
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/auth/ldap/Helper.java b/gerrit-server/src/main/java/com/google/gerrit/server/auth/ldap/Helper.java
index d48aa3e..4c29c9b 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/auth/ldap/Helper.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/auth/ldap/Helper.java
@@ -17,7 +17,6 @@
 import com.google.common.base.Throwables;
 import com.google.common.cache.Cache;
 import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.Maps;
 import com.google.gerrit.common.data.ParameterizedString;
 import com.google.gerrit.reviewdb.client.AccountGroup;
 import com.google.gerrit.server.account.AccountException;
@@ -38,7 +37,6 @@
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
-import java.util.Map;
 import java.util.Properties;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;