Remove LoggedInFlow

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=137444791

java/google/registry/flows/FlowUtils.java

@@ -0,0 +1,37 @@
+// Copyright 2016 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.flows;
+
+import google.registry.flows.EppException.CommandUseErrorException;
+
+/** Static utility functions for flows. */
+public final class FlowUtils {
+
+  private FlowUtils() {}
+
+  /** Validate that there is a logged in client. */
+  public static void validateClientIsLoggedIn(String clientId) throws EppException {
+    if (clientId.isEmpty()) {
+      throw new NotLoggedInException();
+    }
+  }
+
+  /** Registrar is not logged in. */
+  public static class NotLoggedInException extends CommandUseErrorException {
+    public NotLoggedInException() {
+      super("Registrar is not logged in.");
+    }
+  }
+}