Attempt to fix onos-master job issue.

- Temporary workaraound for onos-master job failing with:
   javadoc: error - No public or protected classes found to document.

Change-Id: I3b22d80d9a8716d7c462167df389f19aa4dfae3a

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * 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 org.onosproject.provider.lisp.device.impl;
+
+/**
+ * Remove me.
+ */
+@Deprecated
+public abstract class PlaceHolder {
+
+}