LfsLocksHandler: Simplify lambda expression

Import Collectors.groupingBy as static.

Remove redundant parentheses, braces, and return statement.

Change-Id: I53155f152c6a5088232036861e48f5d5996410be

src/main/java/com/googlesource/gerrit/plugins/lfs/locks/LfsLocksHandler.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/lfs/locks/LfsLocksHandler.java b/src/main/java/com/googlesource/gerrit/plugins/lfs/locks/LfsLocksHandler.java
index c4a1ad3..48f6c17 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/lfs/locks/LfsLocksHandler.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/lfs/locks/LfsLocksHandler.java
@@ -14,6 +14,8 @@
 
 package com.googlesource.gerrit.plugins.lfs.locks;
 
+import static java.util.stream.Collectors.groupingBy;
+
 import com.google.common.cache.CacheLoader;
 import com.google.common.cache.LoadingCache;
 import com.google.common.collect.ImmutableList;
@@ -29,7 +31,6 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
-import java.util.stream.Collectors;
 import org.eclipse.jgit.lfs.errors.LfsException;
 
 @Singleton
@@ -117,11 +118,7 @@
     LfsProjectLocks locks = projectLocks.getUnchecked(project);
     Map<Boolean, List<LfsLock>> groupByOurs =
         locks.getLocks().stream()
-            .collect(
-                Collectors.groupingBy(
-                    (in) -> {
-                      return in.owner.name.equals(user.getUserName().get());
-                    }));
+            .collect(groupingBy(in -> in.owner.name.equals(user.getUserName().get())));
     return new LfsVerifyLocksResponse(groupByOurs.get(true), groupByOurs.get(false), null);
   }