Add request/auth package to Nomulus release

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=147087621

java/google/registry/request/auth/AuthResult.java

@@ -0,0 +1,61 @@
+// 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.auth;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import com.google.auto.value.AutoValue;
+import com.google.common.base.Optional;
+import javax.annotation.Nullable;
+
+/**
+ * Results of authentication for a given HTTP request, as emitted by an
+ * {@link AuthenticationMechanism}.
+ */
+@AutoValue
+public abstract class AuthResult {
+
+  public abstract AuthLevel authLevel();
+
+  /** Information about the authenticated user, if there is one. */
+  public abstract Optional<UserAuthInfo> userAuthInfo();
+
+  public boolean isAuthenticated() {
+    return authLevel() != AuthLevel.NONE;
+  }
+
+  static AuthResult create(AuthLevel authLevel) {
+    return new AutoValue_AuthResult(authLevel, Optional.<UserAuthInfo>absent());
+  }
+
+  static AuthResult create(AuthLevel authLevel, @Nullable UserAuthInfo userAuthInfo) {
+    if (authLevel == AuthLevel.USER) {
+      checkNotNull(userAuthInfo);
+    }
+    return new AutoValue_AuthResult(authLevel, Optional.fromNullable(userAuthInfo));
+  }
+
+  /**
+   * No authentication was made.
+   *
+   * <p>In the authentication step, this means that none of the configured authentication methods
+   * were able to authenticate the user. But the authorization settings may be such that it's
+   * perfectly fine not to be authenticated. The {@link RequestAuthenticator#authorize} method
+   * returns NOT_AUTHENTICATED in this case, as opposed to absent() if authentication failed and was
+   * required. So as a return from an authorization check, this can be treated as a success.
+   */
+  public static final AuthResult NOT_AUTHENTICATED =
+      AuthResult.create(AuthLevel.NONE);
+}