ACCUMULO-3738 Restore o.a.a.t.i.Tracer to get Hive working again.

trace/src/main/java/org/apache/accumulo/trace/instrument/Tracer.java

@@ -0,0 +1,29 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.apache.accumulo.trace.instrument;
+
+/**
+ * ACCUMULO-3738: Temporary fix to keep Hive working with all versions of Accumulo without extra burden on users. Hive referenced this class in the build-up of
+ * the classpath used to compute the answer to a query. Without this class, the accumulo-trace jar would not make it onto the classpath which would break the
+ * query. Whenever Hive can get this patch into their build and a sufficient number of releases pass, we can remove this class.
+ *
+ * Accumulo should not reference this class at all. It is solely here for Hive integration.
+ */
+@Deprecated
+public class Tracer {
+
+}