[HUDI-1352] Add FileSystemView APIs to query pending clustering operations (#2202)

hudi-common/src/main/avro/HoodieRequestedReplaceMetadata.avsc

@@ -0,0 +1,47 @@
+/*
+ * 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.
+ */
+{
+   "namespace":"org.apache.hudi.avro.model",
+   "type":"record",
+   "name":"HoodieRequestedReplaceMetadata",
+   "fields":[
+     {
+         "name":"operationType",
+         "type":["null", "string"],
+         "default": ""
+    },
+    {
+       "name":"clusteringPlan", /* only set if operationType == clustering" */
+       "type":["HoodieClusteringPlan", "null"],
+       "default": null
+    },
+    {
+       "name":"extraMetadata",
+       "type":["null", {
+          "type":"map",
+          "values":"string"
+       }],
+       "default": null
+    },
+    {
+       "name":"version",
+       "type":["int", "null"],
+       "default": 1
+    }
+  ]
+}