Add request/lock to opensource build

This is to fix Kokoro, given the directory added in [] Also, added forgotten keyring/api directory.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=167598465

java/google/registry/request/lock/LockHandler.java

@@ -0,0 +1,45 @@
+// Copyright 2017 The Nomulus Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package google.registry.request.lock;
+
+import java.io.Serializable;
+import java.util.concurrent.Callable;
+import javax.annotation.Nullable;
+import org.joda.time.Duration;
+
+/**
+ * Code execution locked on some shared resource.
+ *
+ * <p>Locks are either specific to a tld or global to the entire system, in which case a tld of
+ * null is used.
+ */
+public interface LockHandler extends Serializable {
+
+  /**
+   * Acquire one or more locks and execute a Void {@link Callable}.
+   *
+   * <p>Runs on a thread that will be killed if it doesn't complete before the lease expires.
+   *
+   * <p>Note that locks are specific either to a given tld or to the entire system (in which case
+   * tld should be passed as null).
+   *
+   * @return true if all locks were acquired and the callable was run; false otherwise.
+   */
+  public boolean executeWithLocks(
+      final Callable<Void> callable,
+      @Nullable String tld,
+      Duration leaseLength,
+      String... lockNames);
+}