LfsLocksHandle: Collapse duplicate if-block

Also fix boolean condition to avoid potential NPE on comparison of
Boolean instance using primitive.

Change-Id: I55d173796a3bdf821cae357aaaaca8f19ad80b95
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 48f6c17..1e75677 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
@@ -101,10 +101,8 @@
 
     LfsLock lock = hasLock.get();
     Optional<String> username = user.getUserName();
-    if (username.isPresent() && lock.owner.name.equals(username.get())) {
-      locks.deleteLock(lock);
-      return new LfsLockResponse(lock);
-    } else if (input.force) {
+    if ((username.isPresent() && lock.owner.name.equals(username.get()))
+        || Boolean.TRUE.equals(input.force)) {
       locks.deleteLock(lock);
       return new LfsLockResponse(lock);
     }